Surface Runoff Coefficient Research Articles

Restored vegetation dominates the decrease in surface and subsurface runoff on the Loess Plateau

Understanding the runoff generation response to environmental changes at the basin scale can provide insights into the evolution of hydrological processes. The objective of this study is to detect and attribute the changes in surface and subsurface runoff in the Chinese Loess Plateau, a region with significant environmental and hydrological changes in the past several decades, to understand how and to what extent the runoff generation can be changed. Taking 13 basins (comprising 56 hydrological stations) on the Chinese Loess Plateau as the study area, we identified rainfall-runoff events and established indicators (event surface runoff coefficient, event timescale, normalized event peak discharge, baseflow, and baseflow index) to characterize the runoff generation, and further attributed the changes in runoff generation characteristics before (1961–2000) and after (2001–2019) the revegetation project. In particular, we inversely estimated the parameters of Soil Conservation Service Curve Number (SCS-CN) to analyze the initial abstraction and potential maximum retention under changing environment. Surface and subsurface runoff significantly decreased, with the surface runoff coefficient and baseflow decreasing by 34 % ± 24 % and 26 % ± 23 %, respectively. The surface runoff hydrograph became flatter with a 75 % decrease in the normalized event peak discharge and 82 % increase in the timescale of surface runoff, respectively. Normalized Difference Vegetation Index (32 %) and population (34 %) dominated the increase in the potential maximum retention, with 84 % of stations experiencing growth exceeding 100 %. The reduction in surface runoff can be primarily attributed to the enhanced soil infiltration due to revegetation and other human activities. Higher evapotranspiration resulting from revegetation was likely the dominant factor leading to the decrease in subsurface runoff. This study detailed the impacts of revegetation on surface and subsurface runoff generation, which can enhance our understanding of hydrological changes.

Integrating topographic factors for effective urban sponge construction in mountainous regions: A case study

The construction of sponge cities in mountainous areas is crucial to achieving high-quality development in these regions. Owing to rugged terrain, significant changes in elevation, and uneven distribution of cities, the construction of sponge cities in mountainous areas faces challenges such as difficulties in clearing mountains and roads, high cost, and varying regional development requirements. However, there is currently limited research focusing on the impact of terrain on sponge city construction plans. In this study, we developed an optimal low impact development (LID) system layout method based on the annual runoff control rate. This study suggests implementing LID plans in stages to balance cost-effectiveness and enhance resilience. The optimized case1_100 scheme, which takes regional differences into account, can effectively achieve a runoff control coefficient of less than 0.25 in 98.86% of the area. Remarkably, this achievement comes at a significantly lower total cost of only 1.22 billion RMB compared to the unoptimized case2_100 scheme (which does not consider regional differences) with a cost of 3.03 billion RMB. Interestingly, the optimized case1_100 plan, selected using the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) method, has an LID layout that is closely related to the surface terrain. Structural equation modeling analysis indicates that terrain affects land types, which in turn impacts the surface impermeability and runoff coefficients, ultimately influencing the corresponding LID deployment plan. The coefficients of relative elevation and slope on the final plan are determined as −0.13 and −0.77, respectively, with a high overall explanatory power of 0.84. This indicates that terrain characteristics have a significant impact on the spatial patterns and surface features of typical mountainous cities in China and the optimal LID strategy largely depends on the initial terrain conditions. This study provides valuable insights for optimizing LID construction in sponge cities, particularly in the context of new mountainous urban planning.

Impact of extreme rainfall events on soil erosion on karst Slopes: A study of hydrodynamic mechanisms

As global warming intensifies, frequent extreme rainfall events cause severe soil erosion. ​However, the impact of extreme rainfall on erosion on karst slopes and its hydrodynamic mechanisms are still poorly understood. This study aims to examine how extreme rainfall events and slope gradient affect soil erosion on karst slopes and its underlying dynamic mechanisms. Simulation experiments were performed in a steel tank that mimicked the dual hydrological structure of a karst slope, using various rainfall intensities (50, 105, 115, 125, and 145 mm·h−1) and slope gradients (5°, 15°, and 25°). The results show that in the event of extreme rainfall (105 – 145 mm·h−1), there was a substantial increase in the surface runoff coefficient, rising from 48.85 % to 89.79 %, representing an 83.81 % increase. Surface erosion was found to be the predominant factor on the slope, contributing to 98.74 % to 99.98 % of the overall sediment output, while underground sediment coefficient ranged from only 0.02 % to 1.26 % under same conditions. The unit stream power emerged as the most suitable hydrodynamic parameter for characterizing surface sediment yield (SS), with a critical threshold of unit water flow power for surface erosion identified at 0.006 m·s−1. Constructing a surface erosion model (R2 = 0.969) based on runoff velocity, rain intensity, and slope yields higher accuracy than the model (R2 = 0.966) based solely on runoff modulus, rain intensity, and slope. For the most precise predictions, it is recommended to combine runoff modulus and velocity with rainfall intensity and slope when constructing the surface erosion prediction model(R2 > 0.999). This study enhances understanding of extreme rainfall’s effect on soil erosion in karst slopes and backs the creation of prediction models for such events. Our insights offer fresh perspectives for soil and water conservation, aiding in the formulation of precise erosion control strategies for karst slopes.

Response of Soil Moisture to Four Rainfall Regimes and Tillage Measures under Natural Rainfall in Red Soil Region, Southern China

Investigating the effects of natural rainfall on the soil moisture for sloping farmland is extremely important for comprehending a variety of hydrological processes. Rainfall regimes can elicit different responses to soil moisture at the depth of soil layers, and the responses may differ depending on the landscape position of the sloping farmland. This paper utilized the surface runoff natural rainfall and soil moisture measured on sloping farmland with conventional tillage and contour tillage in the red soil area of China to investigate the influence of natural rainfall events on soil moisture content and to evaluate if the response results were consistent across the four rainfall regimes. Natural rainfall events were classified into different four regimes in line with rainfall duration, rainfall amount, and the maximum 30 min rainfall intensity (I30) by the k-means clustering method, including advanced, intermediate, uniform and delayed regimes. The result showed that the advanced regime was the predominant one in the study area, which represented 45.9% of the total rainfall events. The rainfall regimes influenced the surface runoff coefficient and runoff depth on sloping farmland for conventional and contour tillage, with the uniform regime generating the highest runoff coefficient (5.20% and 5.82%) and runoff depth (2.00% and 2.05%), respectively. For the conventional tillage, soil moisture at a depth of 0–20 cm increased appreciably when the rainfall amount was larger than 20 mm and larger than 30 mm for the advanced regime. For the contour tillage, soil moisture in 20–40 cm layer increased for the advanced regime when the rainfall amount was larger than 15 mm and 30 mm, while the values were modified with rainfall duration and the antecedent dry day (ADD). A longer rainfall duration had a more obvious effect on soil moisture increasing in deep soil. At a depth of 20 cm, the ADD showed an appreciably positive correlation with the increment in soil moisture, which means that a brief ADD produces a compounding effect for a natural rainfall event. The present results underline the complexity of the effect of the rainfall events on soil moisture under two tillage measures for different rainfall regimes and suggest that the advanced regime significantly affects the distinction of soil moisture and the contour tillage can effectively reduce soil water loss and enhance water storage on the sloping farmland with red soil, presenting a theoretical basis for local soil and water conservation research and sloping farmland conservation tillage management.

Rainfall intensity profile induced changes in surface‒subsurface flow and soil loss as influenced by surface cover type: A long-term in situ field study

Due to global warming, changes in the rainfall intensity profile (i.e., the temporal intensity distribution within a rainfall event) increase the difficulty of accurate erosion prediction and control. Surface cover has been widely used as a critical measure to control soil erosion worldwide. However, the effects of the rainfall intensity profile (RIP) on soil erosion under different surface covers are not fully understood. In this study, long-term in situ field observations of the rain hyetograph, surface runoff coefficient (SRC), subsurface flow rate (SFR), and soil loss rate (SLR) from bare land, litter cover and grass cover were conducted over 11 consecutive years in the red soil hilly region of southern China. According to the occurrence time of the most intense rainfall, 226 erosive events were classified into four RIP patterns: advanced, intermediate, delayed, and uniform patterns. The results indicated that the advanced pattern with short duration–high intensity and the delayed pattern with long duration–high depth contributed to 73.45% of the total erosive events. For bare land, advanced events were the dominant pattern producing surface runoff and soil erosion, accounting for 57.24% and 75.17%, respectively, of the total surface runoff and erosion. The average SRC and SLR from the advanced pattern were 1.29–2.42 times and 2.52–39.78 times greater than those from the other patterns, respectively. The delayed pattern contributed to subsurface flow, and the average SFR was 1.27–2.17 times greater than that of the other patterns. Furthermore, surface cover significantly reduced surface runoff and erosion and increased subsurface flow, especially under the advanced pattern. Both surface cover measures were equally effective in controlling surface runoff and erosion, but the increase in subsurface flow caused by litter cover was 1.38–2.67 times greater than that caused by grass cover. Advanced pattern events increase the erosion risk on red soil slopes, and surface cover effectively weakens the effect of variation in the RIP pattern on soil erosion. Moreover, surface cover significantly alters the surface‒subsurface flow distribution pattern for all the RIP patterns. This study highlights the crucial importance of rain intensity profiles on water erosion and provides a basis for optimizing measures to effectively control soil and water loss under climate change.

Surface runoff in varying forest cover types in Jangkok Watershed, Lombok Island, Indonesia

Abstract. Markum, Rahman FA. 2024. Surface runoff in varying forest cover types in Jangkok Watershed, Lombok Island, Indonesia. Biodiversitas 25: 753-761. Forests in the Jangkok Watershed play an important role in controlling ecological functions and hydrological cycles in Lombok Island, West Nusa Tenggara, Indonesia. This research aims to evaluate the amount of surface runoff in the Jangkok Watershed by looking at various types of forest cover, namely Primary Forest (PF), Disturbed Forest (DF), Candlenut Agroforestry (CA), Mahogany Woodlot (MW), Multistrata Agroforestry (MA) and Simple Agroforestry (SA). The research area was located at altitudes between 250-650 meters above sea level with a slope of 7-43%. Data collected on each type of forest cover included: vegetation characteristics, surface runoff, slope and rainfall. The result shows vegetation cover in the studied area varies from moderate to very dense with coverage ranging from 50-90%. The vegetation in PF, DF and MA are characterized by very diverse vegetation, while that in UM, CA and SA it is quite homogeneous. The amount of Surface runoff coefficient varies across forest cover types with PF being the lowest (0.6-1.4%), followed by DF (0.6-1.7%), MA (0.6-1.7%), MW (0.6-2.1%), SA (1.0-2.2%) and CA (1.8-4.3%). Factors that are considered influential in determining the magnitude of surface runoff at the research location are the physical properties of the soil, rainfall intensity, vegetation type, structure and density, and land slope. The findings of this study suggest that more complex vegetation has important role in minimizing surface runoff, highlighting the importance of preserving and protecting this forest type to maintain hydrological function of watershed.

Rainfall Runoff and Nitrogen Loss Characteristics on the Miyun Reservoir Slope

Rainfall intensity and slope gradient are the main drivers of slope surface runoff and nitrogen loss. To explore the distribution of rainfall runoff and nitrogen loss on the Miyun Reservoir slopes, we used artificial indoor simulated rainfall experiments to determine the distribution characteristics and nitrogen migration paths of surface and subsurface runoff under different rainfall intensities and slope gradients. The initial runoff generation time of subsurface runoff lagged that of surface runoff, and the lag time under different rainfall intensity and slope conditions ranges from 3.97 to 12.62 min. Surface runoff rate increased with increasing rainfall intensity and slope gradient; compared with a rainfall intensity of 40 mm/h, at a slope of 15°, average surface runoff rate at 60 and 80 mm/h increased by 2.38 and 3.60 times, respectively. Meanwhile, the subsurface runoff rate trended upwards with increasing rainfall intensity, in the order 5 > 15 > 10°. It initially increased and then decreased with increasing slope gradient, in the order 5 > 10 > 15°. Total nitrogen (TN) loss concentration of surface runoff shows a decrease followed by a stabilization trend; the concentration of TN loss decreases with decreasing rainfall intensity, and the stabilization time becomes earlier and is most obvious in 5° slope conditions. TN loss concentration in subsurface runoff decreased with increasing rainfall intensity, i.e., 40 > 60 > 80 mm/h. The surface runoff rainfall coefficient was mainly affected by rainfall intensity, a correlation between αs and slope gradients S was not obvious, and the fitting effect was poor. The subsurface runoff rainfall coefficient was mainly affected by slope gradient, the R2 of all rainfall intensities was <0.60, and the fitting effect was poor. The main runoff loss pathway from the Miyun Reservoir slopes was surface runoff, which was more than 62.57%. At the same time, nitrogen loss was subsurface runoff, more than 51.14%. The proportion of surface runoff to total runoff increases with the increase of rainfall intensity and slope, with a minimum of 62.57%, and the proportion of nitrogen loss from subsurface runoff also decreases with increasing rainfall intensity but does not change with slope gradient. The order of different runoff modulus types was mixed runoff (surface and subsurface runoff occur simultaneously) > surface runoff > subsurface runoff. The surface and mixed runoff modulus increased significantly with increasing rain intensity under different rain intensities and slope gradients. Overall, rainfall intensity significantly affected slope surface runoff, and slope gradient significantly affected nitrogen loss.

Regional scale terrace mapping in fragmented mountainous areas using multi-source remote sensing data and sample purification strategy

As a stepped cross section of farmland built along the contour lines, terrace is widely distributed on hill-slopes. It changes the original surface slope and runoff coefficient, reduces soil nutrient loss, and has become the most important soil erosion control measure in China. Accurate terrace mapping at regional scale is crucial for soil conservation, agriculture sustainability and ecological planning. Due to the influence of cloudy and rainy weather, poor data availability makes it difficult to identify terrace distribution only using optical remote sensing images in mountainous areas. In this study, we incorporated multi-spectral optical and SAR data, features of terrain, texture and time sequence information, and proposed a pixel-based supervised classification method based on sample purification strategy to obtain a 10 m resolution terraced map in a plateau mountainous region. With 610 terrace/non-terrace validation sample data, 10-fold cross-validation was used to test the classification results. For identified terrace, the values of Overall Accuracy (OA), Producer's Accuracy (PA) and User's Accuracy (UA) stay stable above 90 %, the F1 score and Kappa coefficient show the smallest fluctuation and is stable in the range of 0.90–0.93 and 0.81–0.87, respectively. The accuracy evaluation of grid units show that the uncertainty of the terrace distribution is mainly concentrated in the north and south of the study area. Slope cultivated land, low-slope terrace and non-agricultural vegetation are easily mixed due to the heterogeneity of terrace features and the spectrum similarity among these land types. It should be noted that the features of time series and texture play a key role in the terrace recognition process, rather than terrain factors, which is different from previous studies. The sample purification strategy proposed provides a more reliable regional scale terrace distribution map compared to the existing product, and is potentially transferable to other mountainous areas as a robust approach for rapid identification of terrace.

On the relationship between surface runoff and impervious area in the urban RPA (Receiving Pervious Area)-DIA (Disconnected Impervious Area) system: A simple equation expressing the sensitivity of runoff to changes in imperviousness

The urban RPA (Receiving Pervious Area)-DIA (Disconnected Impervious Area) system is the sub-catchment with a typical land distribution pattern where the connectivity between impervious area and drainage is disconnected by pervious area in the context of Low Impact Development (LID). The rainfall-runoff response of the RPA-DIA system is complex and plays an important role in LID management, which is not yet fully understood. In this study, to systematically learn the rainfall-runoff response of the RPA-DIA system, an indoor rainfall simulation experiment was applied to a laboratory RPA-DIA system, and an integrated surface-subsurface flow model was used to simulate the hydrological processes of actual-scale RPA-DIA systems with consideration of numerous rainfall and underlying surface conditions. Both the laboratory experiment and the numerical simulations show a segmented linear runoff-imperviousness relationship for the RPA-DIA system. A threshold of impervious area exists in the runoff-imperviousness relationship, and when the impervious area is less than the threshold, the surface runoff coefficient is zero, otherwise the surface runoff coefficient increases with impervious area in a generally linear trend. We define the slope of the linear trend as the R-I sensitivity (sensitivity of runoff to imperviousness), which is the key metric to determine the runoff-imperviousness relationship. We further explored how the R-I sensitivity changes between different rainfall and RPA conditions (e.g., different LID facilities and initial soil moistures) and found that both the laboratory experiment and the numerical simulations suggest a very simple equation to express the R-I sensitivity (RISE, Runoff-Imperviosness Sensitivity Equation) in terms of rainfall depth and intensity, including three parameters indicating the specific RPA conditions. Based on the segmented linear relationship and RISE, we have established a framework that vividly presents the rainfall control behavior of a specific RPA under different rainfall events, which can be a simple tool to provide cost-effective guidelines for LID facilities adapting to current or future rainfall characters.

The Effect of Land Cover Changes on Surface Runoff Using the Soil and Water Assessment Tool in the Bila Watershed

Changes in land cover have a negative impact on land and water resources that occur in the watershed area. This study aims to analyze changes in land cover in 2016 and 2021 and their effects on surface runoff in the Bila Watershed. Analysis of land cover change using the Geographic Information System approach, and then analyzing the effect of land cover change on surface runoff from the results of the Soil and Water Assessment Tool Model. The results showed that the land cover of Bila Watershed when experiencing the highest change was in shrubs of 680.29 ha, dryland agriculture covering an area of 520.99 ha and secondary dryland forest covering an area of 155.76 ha. The effect of land cover changes on surface runoff varies. The highest increase in surface runoff was in shrub cover change to agricultural land and open land while the lowest increase in surface runoff was with changes in primary dryland forest land cover to secondary dryland forest. The surface runoff coefficient of the Bila Watershed in 2016 was included in the good category with a value of 0.16 while in 2021 was included in the moderate category with a value of 0.26.

Optimized Design of Sponge-Type Comprehensive Pipe Corridor Rainwater Chamber Based on NSGA-III Algorithm

Currently, most of the studies using optimization algorithms to mitigate the urban flooding problem have no more than three optimization objectives, and few of them take the operation status of the traditional drainage system as one of the optimization objectives, which is not conducive to the overall design of the city. This study proposes to mitigate the urban flooding problem by using a sponge-type comprehensive pipe corridor rainwater chamber. A four-objective optimization model is established by coupling the Storm Water Management Model (SWMM) and the Non-dominated Sorting Genetic Algorithm-III (NSGA-III), and two traditional drainage system state indicators (pipe overload time, node overflow volume), surface runoff coefficient, and total investment cost are selected as the optimization objectives for solving the problem. The results show that (1) the reduction rates of surface runoff coefficient, pipe overload time, and node overflow volume rate by the optimization model are 37.015–56.917%, 81.538–91.435%, and 51.578–84.963%, respectively; and the total investment cost is RMB 4.311–4.501 billion. (2) The effectiveness of combining SWMM and NSGA-III for an optimization solution is verified, and the relationship between the four objectives is explored. The study may provide useful information for urban flood control.

Spatial pattern of hydrological and erosion behaviour along a dolomite hillslope in Southwest China

Dolomite hillslopes are highly vulnerable to rocky desertification, but the linkages among soil type, runoff mechanisms, and soil erosion remain unclear. During four hydrological years (2018–2021), soil type, plot-scale hydrological and erosion behavior at the upper, middle, and lower slopes along the dolomite hillslope in karst regions of Southwest China were investigated. The results indicated that along the downward slope direction, the degree of soil development gradually increased, forming a typical soil catena pattern. The soil types along the downward direction on the dolomite hillslope gradually transitioned from Entisol to Inceptisol and to Semi-Alfisol. The Entisol was thin and gravelly, with the highest volume ratio of gravel of 75 %. In contrast, Semi-Alfisol was thick and clayey, with the highest volume ratio of fine soil of 97 %. The surface runoff coefficient of the upper slope was only 2.3 % because of the high water infiltration capacity of shallow and rocky soil, and the runoff generation mode was dominated by discontinuous infiltration–excess runoff occurring on rock outcrop patches. Due to the higher soil water content (mean value of 37 %) and frequently occurring lateral flow, the lower slope exhibited the highest surface runoff coefficient of 21 %, mainly as saturation-excess runoff. Catenary soils and their correspondingly divergent hydrological regimes led to average annual soil losses of 0.4, 0.8, and 2.8 t·ha−1·yr−1 at the upper, middle, and lower slopes, respectively. These results advance the understanding of the relationship between hydrology and erosion on karst hillslopes and provide theoretical support for further rocky desertification control.

Influence of antecedent soil moisture content and land use on the surface runoff response to heavy rainfall simulation experiments investigated in Alpine catchments

In small Alpine catchments, floods are mostly triggered by surface runoff generation during convective heavy precipitation events. Their magnitude also depends on the antecedent soil moisture content, which was shown in several previous studies. This study aims at understanding (a) which sites change their surface runoff response to rainfall events with high precipitation intensity under very moist pre-conditions to what extent and (b) on which site characteristics this depends on. Therefore, we conducted repeated rainfall simulation experiments (40–80 m2, 1 h, 100 mm h−1) at 20 sites in five Eastern Alpine areas and analyzed their results on the basis of soil-physical parameters derived from collected soil samples.The hay meadow sites reacted with a strong increase in surface runoff to reduced saturation deficits, the pasture sites showed a smaller but visible response. The forest sites had the highest water retention capacities. The change in the surface runoff response is a function of the saturation deficit at the beginning of the initial experiment (r = −0.58). The soil physical parameters, especially the fine pore fraction (r = 0.56), correlate with the difference of the total surface runoff coefficient between the initial and the repeated experiment. The fine pore fraction also shows a high correlation (r = −0.78) with the saturation deficit at the beginning of the initial experiment, although pores of this fraction were saturated during all experiments. (Non-quantifiable) Land use effects, which in turn influence the soil physical parameters, play an important role in explaining how the surface runoff response in the repeated rainfall simulation experiment differs from the initial experiment. The information on land use and soil characteristics allowed the sites to be categorized into four types in terms of surface runoff disposition and the increase in total surface runoff coefficient in the second rainfall simulation experiment.

Nitrogen and phosphorus losses via surface runoff from tea plantations in the mountainous areas of Southwest China.

Nowadays, there has been a rapid expansion of tea plantations in the mountainous areas of southwest China. However, little research has focused on the pollution problems caused by the losses of nitrogen and phosphorus from tea plantations in this area. Therefore, a field experiment was conducted using the runoff plots in situ monitoring method following farmers' conventional management from 2018 to 2020 in Guizhou Province, southwest China. The characteristics of nitrogen and phosphorus losses from tea plantation in the mountainous area were clarified, and the effect of rainfall intensity on the nitrogen and phosphorus losses were explored. 298 natural rainfall events with a total rainfall of 2258 mm were observed during the 2-year observation period, and erosive rainfall accounted for 78.1% of the total rainfall. The total surface runoff amount was 72 mm, and the surface runoff coefficient was 3.19%. The total nitrogen (TN) and total phosphorus (TP) concentrations in the surface runoff ranged from 0.68 to 14.86 mg·L-1 and 0.18 to 2.34 mg·L-1, respectively. The TN and TP losses from tea plantations were 1.47 kg N ha-1 yr-1 and 0.210 kg P ha-1 yr-1. Rainfall intensity directly and significantly affected the surface runoff and nitrogen and phosphorus loss. Where 72.6% of the cumulative rainfall, 92.5% of the total surface runoff amounts, 87.4% of total nitrogen loss, and 90.5% of total phosphorus loss were observed in rainfall events above 10 mm. Taken together, the results provide scientific guidance for quantifying the characteristics of nutrient loss in subtropical mountain tea plantations.

Optimal designs of LID based on LID experiments and SWMM for a small-scale community in Tianjin, north China

Urban flooding and waterlogging are becoming increasingly serious due to rapid urbanization and climate change. The stormwater management philosophy of low-impact development (LID) has been applied in urban construction to alleviate these problems. The selection and placement of LID designs are the most important tasks. In this study, LID experiments were performed to calibrate the Storm Water Management Model (SWMM). Then, a multi-objective optimization model, which adopted the minimum surface runoff coefficient, surcharge time, and investment cost as objectives, was established by coupling the SWMM and non-dominated sorting genetic algorithm-II (NSGA-II). Hydrological simulations were performed with the SWMM, and optimal calculations were conducted with NSGA-II. Real-coded optimal variables containing detailed size and location information of multiple LID measures were generated, and a decision space for LID design selection was obtained. The optimization designs reduced the surface runoff coefficient from 0.7 to approximately 0.5, the conduit surcharge duration was reduced from 1.62 h to 0.04–0.47 h, and the total investment cost only ranged from 395,000–872,000 ¥. Thus, the optimization model could achieve synchronous optimization of all objectives. This study could provide valuable information for LID design with the aim of urban flooding and waterlogging control.

Groundwater Potential in Unconfined Aquifers Using a Landform Approach in Gorontalo City

This research aimed to determine the potential of the unconfined aquifer in Gorontalo City based on the landform approach. The landforms in Gorontalo City consist of alluvial plains of lake deposits, floodplains of river deposits, alluvial fans of lake deposits, hills of structural fractures of reef limestones, hills of structural fractures of pinogu volcanic rocks, and hills of intrusive bone diorite. The method used consisted of a meteorological approach in the southern hills of Gorontalo City and a dynamic approach on the plains of Gorontalo City. The calculation of groundwater availability using a meteorological approach is 421.561,67 m3/year in the structural limestone reef fractures hill, 1.198.975,33 m3/year in the structural pinogu volcanic fractures hill, and 373.062,86 m3/year in the intrusive bone diorite hill, with a total of groundwater availability using the meteorological approach, is 1.993.599,87 m3/year. Groundwater availability using a dynamic approach was 2.621.535,19 m3/year or a discharge of 49,26 lt/sec (large) in the alluvial plain of lake sediment, discharge of 17,19 lt/sec (large) in the floodplain of river sediment, and discharge of 16,65 lt/sec (large) in the alluvial fan of lake sediment. The potential value of groundwater using the dynamic method is greater than the meteorological approach because of the amount of evapotranspiration, surface runoff, and crop coefficient.

Factors influencing the spatial and temporal variations of surface runoff coefficient in the Red River basin of Vietnam

Factors influencing the spatial and temporal variations of surface runoff coefficient in the Red River basin of Vietnam

An evaluation of rural ecological environment carrying capacity under rural land commercial development

In order to improve the accuracy and efficiency of rural eco-environmental carrying capacity assessment, this paper proposes a new rural eco-environmental carrying capacity assessment method under rural land commercialisation development based on combined weighting method. Firstly, the weighted average method is used to calculate the rural surface runoff coefficient covering the whole area and determine the soil erodibility factor. Secondly, by realising the weighting of the rural ecological environment carrying capacity using principal component analysis (PCA), and calculating the subjective weight of each evaluation index by an analytic hierarchy process, a multi-level evaluation index system is established. The PCA weighting and subjective weighting is then combined to form combined weighting. Finally, the objective function of maximising the carrying capacity of rural ecological environment resources is constructed to realise the evaluation of carrying capacity. The experimental results show that the evaluation accuracy of this method is as high as 99.68%; and the evaluation time is short.

Land Use Changes and Ecosystem Services: The Case Study of the Abruzzo Region Coastal Strip

Consistent and optimized territorial planning, imply the use of numerous variables aimed at improving life quality and reduction of environmental impacts. The resilience of the territory to climate change threats is strongly linked to its progressive transformation. This fact is extremely evident in coastal systems, which are intrinsically fragile systems due to their high environmental value and strong anthropogenic pressure. The existing tools and techniques provide to outline future transformation effects through the scenarios analysis. This work has the objective to evaluate the effects of land use changes in the territory of the Abruzzo coast. The conversion from natural soils to artificial uses has a significant impact on several ecosystem services. The regulation services considered in this work are flood regulation, carbon storage and sequestration, and habitat for biodiversity. The first is directly connected to soil sealing which determines a reduction of water infiltration with the consequent overloading of the existing sewerage systems. The quantitative evaluation is made using the concept of surface runoff coefficient. Instead, the estimation of the last two ecosystem services has been made using InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs) models, specifically the Carbon Storage and Sequestration model and the Habitat Quality model. The results show that Land Use Changes (2012–2018) caused a potential increase of 10% in runoff and an annual Carbon Sequestration loss estimated at about €820,000.

Impacts and sensitivity analysis of imperviousness area and connectivity on surface runoff under a plot‐scale rainfall simulation experiment

AbstractUrbanization has had a major impact on runoff process, which is not fully understood. In this study, a plot‐scale rainfall‐runoff simulation experiment was conducted in an experimental field to evaluate the effects of imperviousness and its connectivity on surface runoff. A total of 11 underlying surface scenarios with different impervious area and two imperviousness connectivity conditions were designed. For each scenario, two rainfall intensities and two initial soil moistures were applied. The results show that the relationship between the surface runoff coefficient and the impervious area under fixed imperviousness connectivity, rainfall intensity, and initial soil moisture represents a strong linear trend. With high antecedent soil moisture, imperviousness arranging in disconnected pattern can lead to initially lower but later higher outflow rate compared to imperviousness arranging in connected pattern. The sensitivity of the runoff coefficient to impervious area, which represents increased runoff coefficient per unit impervious area, is negatively related to the rainfall intensity as well as the initial soil moisture but positively related to the imperviousness connectivity. These results indicate that the impacts of the impervious surface on runoff are not only related to its connectivity, but also the original soil condition before sealing: the higher infiltration capacity of the original soil, the greater hydrological impacts caused by soil sealing.