Thermodynamic Mechanisms and Parametric Landscape Design for Urban Water Bodies in Local Thermal and Humid Environment Regulation

The combined effects of global urbanization and climate change have significantly intensified the urban heat island effect [1-3], causing imbalances in local thermal and humid environments [4], which pose severe threats to human comfort, building energy efficiency, and the stability of urban ecosystems. Against this backdrop, precise microclimate regulation based on thermodynamic principles [5, 6] has become a key breakthrough for mitigating the heat island effect and optimizing urban living environments. Urban water bodies, as natural thermodynamic regulators of local thermal and humid environments [7, 8], redistribute energy and mass through key thermodynamic processes such as evaporation phase change, radiation exchange, and convective diffusion. Their application potential in alleviating the heat island effect has received widespread attention. However, existing studies still face core bottlenecks: insufficient coupling between thermodynamic mechanism analysis and landscape design parameters [9], which often focuses on surface-level observations and parameter associations, lacking in-depth research on process-parameter-effect coupling from a thermodynamic perspective; meanwhile, multi-scale thermodynamic transfer laws remain unclear [10], resulting in a lack of systematization in landscape parameterization design systems, making it difficult to meet the need for precise thermodynamic control in engineering practice.

A review of domestic and international research progress shows that the thermodynamic fundamental research on thermal and humidity regulation by urban water bodies has focused on the application and modification of energy balance equations in water body-atmosphere systems, as well as quantitative models for phase changes and heat transfer processes. However, existing results still have notable limitations in multi-process coupling simulations and multi-scale linkage analysis. In research on the correlation between water bodies and landscape parameters, scholars have focused on the impact of landscape parameters such as morphology, configuration, and attributes on thermal and humidity effects [11-13], but there is a common issue of disconnect between thermodynamic mechanisms and parameter control, failing to reveal the intrinsic thermodynamic paths through which parameters affect thermal and humidity effects. Although multi-scale microclimate regulation studies have discovered differences in urban water body thermal and humidity regulation effects at different scales [14, 15], the current parameterization system still lacks scientific scale division and clarity in cross-scale transfer mechanisms. In summary, existing research has not formed a complete research system centered on thermodynamic principles, coupled with landscape parameters, and spanning multiple scales. This research gap provides a clear academic entry point and core exploration direction for this study.

Based on the above research background and existing shortcomings, this study proposes three core scientific questions: First, in the cooling and humidifying effects of urban water bodies in typical climatic regions, what is the relative proportion of contributions from evaporation latent heat and radiation regulation, and what are the landscape parameters that dominate and their corresponding thermodynamic control thresholds? Second, how do single or combined landscape parameters regulate the energy flux distribution at the water-atmosphere interface through thermodynamic pathways, and what are the thermodynamic synergistic or antagonistic mechanisms under multi-parameter interactions? Third, what are the thermodynamic transfer laws at the micro-interface, meso-patch, and macro-network scales, and how do the dominant thermodynamic mechanisms and core design parameters match at different scales? The core objective of this study is to systematically reveal the thermodynamic mechanisms of water body thermal and humidity regulation coupled with landscape parameters, elucidate multi-scale thermodynamic transfer laws, and construct a multi-scale collaborative landscape parameterization system to provide scientific basis and technical support for precise thermodynamic control of urban microclimates.

To achieve the above research objectives, this study adopts a multi-method integration technical approach, including pilot case analysis, field observation experiments, indoor control experiments, numerical simulation, and thermodynamic mechanism analysis with statistical modeling. The overall technical route follows the logical chain of "pilot case identification of phenomena → theoretical foundation construction → coupling parameter mechanism analysis → multi-scale parameterization system construction → case verification application", clarifying the thermodynamic analysis focus and technical method connection at each research stage, ensuring the systematic and scientific nature of the research process.

The subsequent chapters of this paper are arranged as follows: Chapter 2 verifies the thermal and humidity regulation effects of water bodies through pilot case studies and proposes core scientific hypotheses; Chapter 3 conducts thermodynamic process observations and mechanism analysis of coupled landscape parameters; Chapter 4 constructs a multi-scale collaborative landscape parameterization system; Chapter 5 verifies the effectiveness of the parameterization system through case applications; and finally, the research results and scientific value are summarized through discussions and conclusions. The innovations of this research are mainly reflected in four aspects: first, based on empirical analysis of pilot cases, the research starting point is elevated from literature gaps to observational phenomena and scientific hypotheses, enhancing the rigor of the research logic; second, a deep-coupled analysis framework of landscape parameters-thermodynamic processes-thermal and humidity effects is constructed, analyzing parameter regulation mechanisms from the thermodynamic principle level, breaking through the research bottleneck of mechanism-parameter disconnect; third, multi-scale thermodynamic transfer laws are clarified, and a parameterization system with precise matching for each scale is established, improving the systematization and thermodynamic control targeting of the design system; fourth, thermal and humidity optimization design guidelines are generated for different climatic regions and scales, achieving efficient translation of theoretical results into engineering practice.

3.1 Observation scheme design and implementation

Based on the pilot case analysis results, a waterfront area in the subtropical monsoon climate zone of East Lake, Wuhan, is selected as the core observation area. This area features both open water bodies and shoreline transition zones, and the surrounding vegetation coverage gradient can be controlled, making it suitable for thermodynamic process observation of coupled landscape parameters. The observation design focuses on "parameter gradient control" and sets two types of key landscape parameter gradients: water depth gradient, which includes 0.5 m, 1.0 m, and 1.5 m levels, covering the common water depth range of urban artificial lakes; and vegetation coverage gradient, which includes four levels: 0% for bare shore, 20% for sparse herbaceous vegetation, 40% for herbaceous + shrub vegetation, and 60% for tree-shrub-herb composites, simulating different waterfront greening configuration patterns. Observation points for each parameter gradient are arranged in a nested layout to ensure consistency in the meteorological background field, with adjacent observation points spaced ≥50 m to avoid mutual interference.

The observation indicator system is divided into three main categories, covering thermodynamic processes, landscape parameters, and environmental background: Thermodynamic Core Indicators include sensible heat flux, latent heat flux, net radiation flux, water body-atmosphere temperature difference, and water vapor pressure deficit, with heat flux being the core observation item. Landscape Parameter Indicators include real-time water depth, shoreline complexity, and vegetation coverage, which are dynamically monitored to capture spatial-temporal variations in parameters. Environmental Indicators include air temperature, relative humidity, 10m wind speed, and precipitation, which are used to calibrate environmental interference in thermodynamic processes. The observation method uses a multi-device collaborative system: heat flux observation is conducted using a eddy covariance system and gradient observation tower to ensure the accuracy of flux data; meteorological and landscape parameters are monitored using automatic meteorological stations with a sampling interval of 10 minutes for continuous monitoring; dynamic changes in vegetation coverage and shoreline morphology are verified weekly using UAV aerial photography. The observation period covers a typical week during the summer heat period, from late July to early August, recording the full diurnal variation process from 00:00 to 24:00, and a total of 168 hours of valid observation data are obtained.

3.2 Coupling mechanism of evaporation-latent heat process and landscape parameters

The thermodynamic analysis of the evaporation-latent heat process is based on the energy balance of the water body-atmosphere interface and phase change principles. The core control equation uses the Penman-Monteith equation to quantify the evaporation rate and latent heat flux:

$L E=\frac{\Delta\left(R_n-G\right)+\rho_a c_p \frac{e_s-e_a}{r_a}}{\Delta+\gamma\left(1+\frac{r_s}{r_a}\right)}$                (3)

where, Δ is the slope of the saturation water vapor pressure-temperature curve, ρ_a is air density, c_p is the specific heat capacity of air at constant pressure, e_s−e_a is the vapor pressure deficit, r_a is aerodynamic resistance, r_s is surface resistance, and γ is the psychrometric constant. Observational results show that the daily variation of evaporation latent heat flux during the summer heat period follows a unimodal curve, with the peak occurring between 12:00 and 14:00, and the average value ranging from 85 to 120 W·m⁻². The vapor pressure deficit and the water body-atmosphere temperature difference are the dominant driving factors, and together, they explain 78% of the variation R² in latent heat flux.

Landscape parameters have a significant gradient difference in regulating the evaporation-latent heat process. Under the water depth gradient, latent heat flux increases and then decreases with increasing water depth: the peak latent heat flux at 1.0 m water depth reaches 118 W·m⁻², which is 28.3% higher than at 0.5 m and 14.6% higher than at 1.5 m. Vegetation coverage shows a linear positive correlation with latent heat flux, with a 42.1% increase in latent heat flux at 60% coverage compared to bare shore. Vegetation strengthens water vapor diffusion by reducing aerodynamic resistance r_a. For every increase of 0.1 in shoreline complexity, latent heat flux increases by 5.3%, attributed to the expansion effect of the interface contact area on the evaporation surface. From a thermodynamic perspective, water depth regulates the surface temperature gradient by altering the heat capacity of the water body: shallow water bodies have low heat capacity, causing rapid warming during the day, which leads to early saturation of e_s−e_a and limits continuous evaporation; deep water bodies have a lag in heat conduction, resulting in insufficient surface temperature increase and weakening the evaporation driving force. Vegetation and shoreline morphology regulate the thermodynamic conditions of water vapor diffusion by adjusting the resistance term r_a, thus enhancing latent heat flux.

3.3 Coupling mechanism of radiation exchange process and landscape parameters

The thermodynamic balance core of the urban water body radiation exchange process is the reconstruction of the net radiation flux balance. The balance equation is:

$R_n=R_{n s}-R_{n l}$                (4)

where, R_ns is the net shortwave radiation flux and R_nl is the net longwave radiation flux. Observational results show that during the summer heat period, the average R_ns of the water body surface is 320 W·m⁻², which is 18.6% lower than the surrounding hard surfaces, mainly due to the higher shortwave reflectivity of the water body. The average R_nl is -105 W·m⁻², which is 23.5% higher than the surrounding hard surfaces, indicating that the water body has a stronger ability to release accumulated heat through longwave radiation. Overall, the average net radiation flux (R_n) of the water body is 215 W·m⁻², which is 12.3% lower than the surrounding surfaces, forming a local radiation energy sink. This is the core thermodynamic basis of the water body’s radiation regulation effect.

Landscape parameters regulate radiation exchange components to achieve precise control of radiation regulation effects. Shoreline material reflectivity is a key parameter affecting R_ns: when high-reflectivity materials are used, the shoreline area’s R_ns is reduced by 26.8% compared to conventional concrete shorelines, significantly reducing radiation energy input. Vegetation coverage reduces the transmission of solar shortwave radiation: when the coverage reaches 60%, the water body surface R_ns is reduced by 31.2% compared to the uncovered area, and this weakening effect is most significant during midday. The influence of building layout is reflected in longwave radiation exchange: in high-density building enclosures, the absolute value of R_nl in the water body decreases by 19.4%, as longwave radiation reflection from buildings inhibits the release of longwave radiation from the water body, causing radiation energy retention. According to radiation transfer theory, vegetation cover attenuates shortwave radiation transmission through leaf scattering and absorption, reducing the accumulated radiation energy on the water surface. Building enclosures, on the other hand, alter the local radiation environment and disrupt the longwave radiation balance between the water body and the atmosphere. This mechanism is particularly prominent in high-density built-up areas.

3.4 Convection-diffusion process and coupling mechanism of landscape parameters

The thermodynamic core of the water body-atmosphere convection-diffusion process is the momentum and energy transfer of the heat and moisture air flow, and its intensity is quantified by the convection heat transfer coefficient h_c, calculated using the Nusselt number correlation:

$N u=0.664 R e^{0.5} P r^{0.33} \mathrm{~h}_c=\frac{N u \cdot \lambda_a}{L}$                  (5)

where, Re is the Reynolds number, Pr is the Prandtl number, λ_a is the air thermal conductivity, and L is the characteristic length. Observational results show that during the summer heat period, the average convection heat transfer coefficient around the water body is 5.2 W·m⁻²·K⁻¹. The diffusion range of heat and moisture air flow is positively correlated with h_c. When h_c > 6.0 W • m⁻² • K⁻¹, the diffusion range can exceed 300 m, which is an increase of 45% compared to when h_c < 4.0 W • m⁻² • K⁻¹.

Landscape parameters significantly affect the convection-diffusion intensity by regulating the air flow movement state. Wind speed is a fundamental driving factor. When the 10m wind speed increases from 1.0 m·s⁻¹ to 3.0 m·s⁻¹, h_c increases by 68.3%, and the heat and moisture diffusion rate increases by 52.1%. An increase in building density inhibits convection diffusion. When density increases from 30% to 70%, h_c decreases by 39.6%, and the diffusion range shrinks to within 150 m, forming a significant airflow retention area. The shape of the water body has a significant effect on airflow guidance. Irregular polygonal water bodies have a 23.5% higher h_c compared to rectangular water bodies because of the local vortices created by the convoluted shoreline that facilitate heat and moisture exchange. From the thermodynamic and fluid dynamics coupling mechanism perspective, the "canyon effect" formed by high-density building enclosures reduces the cross-sectional area for air flow, causing a reduction in wind speed and a subsequent decrease in turbulence intensity, making it difficult for heat and moisture air flows to diffuse effectively, thereby leading to accumulated interface heat flux. Irregular water bodies, on the other hand, optimize the airflow contact path, enhancing interface turbulence mixing, which improves convection heat transfer efficiency. This mechanism provides thermodynamic support for landscape morphology optimization.

3.5 Thermodynamic synergistic/antagonistic mechanisms of multi-parameter interactions

An orthogonal experimental design combined with ENVI-met numerical simulation was used to analyze the heat and moisture effects of multi-parameter interactions. Four key parameters, water depth (A), vegetation coverage (B), shoreline complexity (C), and building density (D), were selected, with a 3-level orthogonal experiment setup. The experimental parameter levels are shown in Table 3. The experimental results show that the contribution of parameter interaction effects to the thermodynamic regulation effect is 35.2%, significantly higher than that of single parameters. The most significant interactions were between water depth-vegetation coverage and shoreline complexity-building density.

Table 3. Orthogonal experiment parameters and level settings

The synergistic and antagonistic effects of multi-parameter interactions have clear mechanistic origins, and the effect characteristics of typical interaction combinations are shown in Table 4. Synergistic effects reflect the combined promotion of thermodynamic processes by parameter combinations: when water depth is 1.0m and vegetation coverage is 40%, the latent heat flux increases by 18.3% compared to the single parameter optimum, with the core mechanism being that appropriate water depth ensures a stable evaporation driving force, and moderate vegetation coverage reduces interface air resistance, thereby coupling to optimize the "evaporation-diffusion" thermodynamic chain. When shoreline complexity is 1.5 and building density is 30%, the convection heat transfer coefficient increases by 22.1%, as the increased interface contact from the complex shoreline and the airflow circulation ensured by the low building density synergistically strengthen heat and moisture transmission. Antagonistic effects arise from the disruption of thermodynamic balance by parameter combinations: when water depth is 0.5 m and building density is 70%, the net radiation flux increases by 15.6% compared to the single parameter scenario, with significant heat and moisture retention. The mechanism is that shallow water bodies warm quickly, leading to increased radiation absorption, while high-density buildings suppress heat diffusion, breaking the energy balance. When vegetation coverage is 60% and shoreline complexity is 2.0, excessive vegetation shading weakens the evaporation driving force, offsetting the contact area advantage from the shoreline complexity, and latent heat flux decreases by 9.8%.

Table 4. Thermodynamic effect characteristics of typical parameter interaction combinations

Table 5. Landscape parameter sensitivity analysis results

Based on variance analysis (ANOVA) and standardized regression coefficient sensitivity analysis, the influence weight of each parameter on the thermodynamic effect was clarified, as shown in Table 5. The core landscape parameter combination selected is water depth 1.0–1.2 m, vegetation coverage 30–40%, shoreline complexity 1.3–1.6, and building density ≤40%. The thermodynamic regulation efficiency in this combination is 42.5% higher than in random parameter combinations. The sensitivity analysis results show that water depth has the highest sensitivity coefficient, followed by vegetation coverage and building density, and shoreline complexity has a sensitivity coefficient of 0.17. These results provide the core weight basis for subsequent parameterization system construction.

5.1 Case area overview and current thermodynamic diagnosis

A residential area in Guangzhou, located in a subtropical summer-heat winter-warm climate zone, is selected as the case study. The area covers a total of 12.6 hectares and includes an artificial lake, surrounded by high-rise residential buildings and hard-paved surfaces. Vegetation is predominantly sparse shrubs. The main climate feature of the area in summer is high temperature and humidity, with an average temperature of 32.5℃ in July and August, and peak daytime temperatures frequently exceeding 38℃, which meets the typical needs for water body heat-moisture regulation optimization in a summer-heat climate zone. To accurately diagnose the current issues, a combination of field observation and ENVI-met numerical simulation is used to systematically collect landscape parameters and thermodynamic indicator data. The core basic data is shown in Tables 6 and 7.

Table 6. Comparison of landscape parameters in the case area before and after optimization

Table 7. Comparison of core thermodynamic indicators in the case area before and after optimization

Table 8. Thermal comfort and thermodynamic efficiency evaluation table for the case area

The current thermodynamic diagnosis results show significant multi-scale thermodynamic imbalance issues in the case area. From the landscape parameter perspective, key meso-scale parameters generally do not meet optimization standards: the water depth is only 0.6 m, below the optimal range for the meso-scale; the shoreline complexity is 1.1, which does not effectively expand the air-liquid contact area; the vegetation coverage is 25% and configured with a single type of shrub, making it difficult to form a synergistic cooling effect; the water body-hard surface ratio is 1:7.2, much lower than the threshold of 1:5. In terms of thermodynamic indicators, the daytime peak latent heat flux in the summer heat period is only 95 W·m⁻², accounting for 40.9% of the net radiation flux, significantly below the effective contribution threshold of 60%, indicating that the evaporation latent heat-dominated cooling mechanism has not been fully activated. Meanwhile, the daytime peak temperature reaches 38.6℃, with relative humidity only at 33.5%, leading to a severe imbalance in the heat-moisture environment. Combining the energy balance analysis, the core issue is identified as insufficient water depth and lack of vegetation coverage, leading to dual deficiencies in evaporation driving force and diffusion efficiency, compounded by the radiation heat accumulation effect caused by excessive hard surface coverage, ultimately resulting in the deterioration of the local heat-moisture environment.

5.2 Optimization design scheme based on parametric system

Based on the multi-scale collaborative parametric system constructed in the previous sections, and combining the current issues and landscape functional requirements of the case area, a progressive optimization scheme for each scale is developed. The core optimization parameters are shown in Table 6. At the micro scale, the focus is on improving the interface heat-moisture exchange efficiency: replace the original concrete shoreline with permeable concrete to reduce the thermal conduction loss between the shoreline and water body; adjust the water body albedo to 0.10 by cleaning the water surface and reasonably configuring aquatic vegetation, controlling the water surface vegetation lodging rate to 12%, thereby optimizing the interface radiation balance and water vapor diffusion resistance conditions.

At the meso scale, the focus is on reconstructing the energy balance of the block: four key optimizations are implemented. First, expand the artificial lake area to 0.51 hectares to meet the threshold requirement of ≥0.5 hectares of water body area in residential areas of the summer-heat climate zone; second, increase the water depth to 1.0 m, matching the optimal water depth range for the meso scale, ensuring that the contribution of evaporation latent heat remains stable above 60%; third, through local shoreline expansion and curve optimization, increase the shoreline complexity to 1.5, expanding the air-liquid contact area to enhance convective heat transfer; fourth, adjust the vegetation configuration to a composite of trees, shrubs, and grass, increase the coverage rate to 42%, and optimize the layout of hard paving, increasing the water body-to-hard surface ratio to 1:4.8, surpassing the 1:5 benefit threshold. At the macro scale, the focus is on the synergy of regional heat-moisture effects: by adding two riparian connected green corridors, the water body connectivity index is increased from 0.4 to 0.7, and the blue-green space coupling degree is increased from 0.28 to 0.45. This creates a connectivity blue-green network of "artificial lake - green corridors - community green spaces" to promote the regional diffusion of cooling effects.

By integrating the optimization parameters for each scale, a complete design scheme is formed that balances thermodynamic regulation and landscape functionality. The artificial lake adopts a "curved shoreline + layered water depth" layout, with a 3-meter wide composite green belt of trees, shrubs, and grass around the shoreline, paired with permeable paving walkways. The connected green corridors use native trees and herbs to ensure shading and transpiration effects in summer. At the same time, the greening configuration around the buildings is optimized, achieving thermodynamic collaborative regulation of "water body - vegetation - buildings." The scheme meets the needs for residents' recreational activities while accurately implementing the parametric indicators for each scale, ensuring the thermodynamic optimization objectives are achieved.

5.3 Thermodynamic optimization effect evaluation

Numerical simulation predictions were carried out using the ENVI-met V5.6 model with coupled thermodynamic equations. The simulation period selected was a typical sunny day in the summer heat period, with a grid resolution of 1m×1m and 20 vertical layers. Input parameters were calibrated based on field observation data, and a comparative analysis of the thermodynamic effect differences between the current situation and the optimized plan was performed. The core evaluation data are shown in Table 8.

The optimization effect on thermodynamic indicators is significant. The daytime peak temperature was reduced from 38.6℃ to 36.3℃, a drop of 2.3℃, which is a 6.0% improvement. The relative humidity increased from 33.5% to 39.7%, a 6.2 percentage point increase, effectively alleviating the imbalance in the heat-moisture environment. Regarding heat flux, the daytime peak latent heat flux increased from 95 W·m⁻² to 142 W·m⁻², a 49.5% increase, and the proportion of latent heat flux to net radiation flux increased from 40.9% to 63.5%, confirming the activation effect of water depth and vegetation optimization on the evaporation latent heat-driven mechanism. The sensible heat flux decreased from 128 W·m⁻² to 86 W·m⁻², a 32.8% reduction, indicating that the improved interface heat exchange efficiency effectively reduced sensible heat release. In terms of spatiotemporal distribution, the cooling and humidifying effect coverage of the optimized plan expanded from the current 150 m to 320 m, achieving an overall improvement in the thermal environment at the block scale. The nighttime temperature dropped by 0.6℃, and relative humidity increased by 3.5 percentage points, showing that the plan also had a positive regulatory effect on the nighttime thermal environment.

The thermal comfort and thermodynamic efficiency evaluation shows that the daytime peak PET index dropped from 41.5℃ to 34.8℃, and the daytime average index PET dropped from 38.2℃ to 33.5℃, significantly improving human thermal comfort. In terms of thermodynamic efficiency, the temperature reduction benefit per unit area increased from 8.7℃·m⁻²/ha to 15.3℃·m⁻²/ha, a 75.9% increase. The comprehensive thermodynamic efficiency value, combining cooling amplitude, humidifying amplitude, and latent heat proportion, increased from 0.52 to 0.74, a 42.3% improvement, indicating that the plan achieved synergistic optimization in energy utilization efficiency and heat-moisture regulation effects.

To verify the reliability of the simulation results, field observations were conducted for one week after the implementation of the optimization plan. The observed data showed: the actual daytime peak temperature was 36.5℃, with a deviation of 0.2℃ from the simulation value; the actual latent heat flux was 139 W·m⁻², with a deviation of 2.1%, indicating that the simulation accuracy meets the engineering verification requirements. Based on the observed data, the multi-scale parametric model was corrected by adjusting the mapping coefficient of vegetation coverage and latent heat flux at the meso scale, which increased the R² of the model prediction to 0.86, further improving the practical adaptability of the parametric system. In summary, the optimization design plan based on the parametric system in this study effectively solves the thermodynamic imbalance problem in the case area, significantly improves heat-moisture regulation efficiency and human comfort, and verifies the scientific and engineering practicality of the parametric system.

(a) Riparian Section 1 (nearshore open area)

(b) Riparian Section 2 (building-adjoining water area)

(c) Riparian Section 3 (vegetation transition zone)

(d) Riparian Section 4 (hard paving adjoining water area)

Figure 3. Air temperature variation in different riparian sections under different vegetation coverage rates

To clarify the role of vegetation coverage in regulating the spatial decay process of urban water body heat-moisture regulation effects, gradient observations and simulations of air temperature were conducted at different riparian sections during the summer heat period. The results shown in the Figure 3 indicate that within the range of 0-100m from the water body shoreline, the air temperature increases significantly as the distance from the shore increases, and vegetation coverage has differentiated regulatory effects on the temperature decay rate and the final stable value: in the nearshore open area, the air temperature with 60% vegetation coverage is 1.8℃ lower than that with 20% coverage, and the temperature stabilization distance is delayed by 15m; in the building-adjoining water area, the cooling advantage of high vegetation coverage is more significant, with 60% coverage resulting in a 2.2℃ lower nearshore temperature compared to 20%, while the temperature rise slope decreases by 30%; in the vegetation transition zone and hard paving-adjoining water area, a similar pattern is observed, with high vegetation coverage effectively extending the cooling effect of the water body and lowering the temperature stabilization value in the farshore area. This result indicates that vegetation coverage optimizes the spatial distribution characteristics of urban water body heat-moisture regulation effects by enhancing the synergistic effects of water vapor diffusion and radiation shielding. It also confirms the parametric standard for meso-scale riparian vegetation configuration — a composite coverage of 30%-50% of trees, shrubs, and grasses in riparian areas in summer-heat climate zones achieves an optimal balance between resource input and cooling effect spatial coverage.

This study conducted a systematic investigation on the thermodynamic mechanism of urban water body heat-moisture regulation and landscape parameterization design. Through pilot case analysis, multi-scale observational experiments, numerical simulations, and case validation, the coupling relationship between landscape parameters, thermodynamic processes, and heat-moisture effects was clarified, and a multi-scale collaborative parameterization system was constructed. The main conclusions are as follows:

(1) The pilot case study confirmed that urban water bodies have significant local heat-moisture regulation effects. In the summer heat period, the temperature reduction can reach 1-4℃, and the humidity increase can range from 3% to 8%. Lakes provide better regulatory effects than rivers. The study identified area, water depth, vegetation coverage, and built density as core influencing parameters. The three core scientific hypotheses proposed were experimentally validated: under the summer heat climate, the contribution of latent heat to cooling effects is no less than 60%, with an optimal water depth threshold of 0.8–1.2 m; shoreline sinuosity and vegetation coverage exhibit significant synergistic effects; and there is a clear thermodynamic transmission path between micro, meso, and macro scales.

(2) The thermodynamic mechanism of urban water body heat-moisture regulation with coupled landscape parameters was clarified. Latent heat evaporation is the dominant process for cooling in the summer heat period, contributing 60%–75%. Its intensity is co-regulated by water depth and vegetation coverage — appropriate water depth ensures evaporation driving force, and moderate vegetation reduces interface diffusion resistance. Radiation exchange contributes significantly in high-density building areas, where shoreline material albedo and building layout influence regulation effects by controlling shortwave radiation input and longwave radiation balance. Convective diffusion efficiency is dominated by water body shape and wind speed. Irregular water bodies can strengthen interface heat exchange, while high-density buildings tend to cause heat and humidity retention. The interactions between multiple parameters have clear thermodynamic origins of synergy or antagonism.

(3) The multi-scale thermodynamic transmission laws were clarified, and parameterization indicators and quantification standards were established with precise matching for each scale. The micro-scale is dominated by interface properties such as water body albedo and shoreline material conductivity for heat exchange efficiency. The meso-scale is dominated by form configuration parameters such as water body area, water depth, and shoreline sinuosity for block energy balance. The macro-scale is dominated by pattern parameters such as water body connectivity and green-blue space coupling for regional heat environment regulation. The scales achieve thermodynamic transmission through the "interface heat flux superposition-patch energy aggregation-regional energy accumulation" path.

(4) The multi-scale collaborative landscape design parameterization system and climate zone-specific design guidelines, verified through a case study in a summer-heat, winter-warm climate residential area, can achieve a 2.3℃ reduction in daytime peak temperature, optimize the heat comfort index (PET) to below 35℃, increase the latent heat flux proportion to 63.5%, and improve the overall thermodynamic efficiency by 42.3%. This system breaks through the traditional research bottleneck of "disconnection between mechanisms and parameters, scale confusion," achieving effective integration of thermodynamic precise regulation and engineering practice, and providing reliable thermodynamic theoretical support and practical technical solutions for urban microclimate optimization.