Runoff Coefficient Research Articles

Pesticide dynamics in agroecosystems: Assessing climatic and hydro-physical effects in a soybean cycle under no-tillage

The high rate of No-Tillage (NT) adoption in Argentina has been followed by conspicuous application of herbicides due to RR crops selection and recently due to weed resistance. In addition, no-tillage in the Rolling Pampa (Argentina) with absence of crop rotation and scarce crop residues, led to physical degradation (low infiltration rates, platy structure development) having strong implications on water dynamics and the risk of soil and water contamination. Several factors can influence the mobility of pesticides in the landscape. However, measurement of soil hydro-physical and climate traits as determinants of pesticide dynamics are still scarce. In this study, pesticides from soil and runoff (Glyphosate, AMPA, S-Metolachlor, Sulfentrazone), and hydro-physical and climatic variables were measured at the field in an entire soybean cycle under NT. Temporal dynamics of runoff and saturated hydraulic conductivity was measured by rainfall simulations and disc permeameters together with soil bulk density, soil moisture, crop residues, rainfall and rainfall erosivity. Besides, soil structure was evaluated through cultural profile method. In the Vertic Argiudoll (silty clay loam) pesticides mobility were related to the number of days after agrochemical application modulated also by heavy natural rainfalls occurred during the experiment that lowered agrochemical concentration mostly in runoff. Temporal hydro-physical properties and spatial soil structural variability, together with strong climatic events governed runoff process affecting pesticides mobility while no strong pesticide accumulation in the plots was observed in this study due to low saturated hydraulic conductivity, high runoff coefficients and poor soil structural traits. Thus, the selection of appropriate agricultural management is a key factor to modify hydro-physical top soil dynamics to change hydrological partition from horizontal to vertical fluxes, in particular in soils with poor structural condition.

Evaluation and Improvement Measures of the Runoff Coefficient of Urban Parks for Sustainable Water Balance

As the impermeable sidewalk area increases in urban areas, diverse problems related to water occur. The purposes of this research were to increase the rainwater infiltration rate through water balance analysis and estimate the runoff coefficient according to land cover types in urban parks. The regression equations and runoff coefficients relative to the rainwater infiltration rate were estimated according to the land cover types and applied to eight urban parks. In the results of the experiment, the runoff coefficient was 0.245 for vegetation areas, 0.583 for permeable sidewalks, 0.963 for sidewalk blocks, and 1.000 for impervious sidewalks, which had 100% outflow. The results show that the vegetation area in urban parks is significantly related to rainfall–runoff, infiltration, and evapotranspiration. The average of eight urban parks was 126.52 mm, indicating that 11.80% of the rainfall was recharged into groundwater. Additionally, the average runoff rate was 498.56 mm, indicating that 46.52% was leaked externally. Therefore, it is suggested to decrease the impermeable sidewalk areas in urban parks. Additionally, extending the waterway, swamp, and gravel sidewalk areas is suggested. Urban parks should be developed in order to contribute to hydrological control through the water balance in urban land use.

Curating 62 Years of Walnut Gulch Experimental Watershed Data: Improving the Quality of Long-Term Rainfall and Runoff Datasets

The curation of hydrologic data includes quality control, documentation, database development, and provisions for public access. This article describes the development of new quality control procedures for experimental watersheds like the Walnut Gulch Experimental Watersheds (WGEW). WGEW is a 149 km2 watershed outdoor hydrologic laboratory equipped with a dense network of hydro-climatic instruments since the 1950s. To improve data accuracy from the constantly growing instrumentation networks in numerous experimental watersheds, we developed five new QAQC tools based on fundamental hydrologic principles. The tools include visual analysis of interpolated rainfall maps and evaluating temporal, spatial, and quantitative relationships between paired rainfall-runoff events, including runoff lag time, runoff coefficients, multiple regression, and association methods. The methods identified questionable rainfall and runoff observations in the WGEW database that were not usually captured by the existing QAQC procedures. The new tools were evaluated and confirmed using existing metadata, paper charts, and graphical visualization tools. It was found that 13% of the days (n = 780) with rainfall and 7% of the runoff events sampled had errors. Omitting these events improved the quality and reliability of the WGEW dataset for hydrologic modeling and analyses. This indicated the effectiveness of application of conventional hydrologic relations to improve the QAQC strategy for experimental watershed datasets.

Ecological restoration stimulates environmental outcomes but exacerbates water shortage in the Loess Plateau.

Restoration is the natural and intervention-assisted set of processes designed to promote and facilitate the recovery of an ecosystem that has been degraded, damaged, or destroyed. However, it can also have an adverse effect on the environment. Thus, assessing an ecological restoration project’s impact is crucial to determining its success and optimum management strategies. We performed a meta-analysis concerning the environmental outcomes during the years 2000–2015 resulting from the “Grain for Green” Project (GFGP) implementation in the Loess Plateau (LP). Data were gathered from 40 peer-reviewed English-language articles chosen from a pool of 332 articles. The results showed that, on average, GFGP increased forest coverage by 35.7% (95% CI [24.15–47.52%]), and grassland by 1.05% (95% CI [0.8–1.28%]). At the same time, GFGP has a positive impact on soil carbon (C) sequestration, net ecosystem production (NEP), and net primary production (NPP), from the years 2000 to 2015 by an average of 36% (95% CI [28.96–43.18%]), 22.7% (95% CI [9.10–36.79%]), and 13.5% (95% CI [9.44–17.354%]), respectively. Soil erosion, sediment load, runoff coefficient, and water yield were reduced by 13.3% (95% CI [0.27–25.76%]), 21.5% (95% CI [1.50–39.99%]), 22.4% (95% CI [5.28–40.45%]) and 43.3% (95% CI [27.03–82.86%]), respectively, from the years 2000 to 2015. Our results indicate that water supply decreased with the increase of vegetation coverage. Therefore, to balance the needs for green space, GFGP policies and strategies should recover, enhance, and sustain more resilient ecosystems.

Infiltrasi dan Aliran Permukaan pada Agroforestri dan Kelapa Sawit

Forest to oil palm plantations conversion has changed soil's physical properties significantly. It caused significant changes in the hydrological cycle and affects the water resources around the research site. One of the strategies that could minimize the negative impact of monoculture oil palm plantations is better plantation management by implementing a mixed cropping system (agroforestry). This study aims to analyze the infiltration, surface runoff, and surface runoff coefficient in agroforestry and monoculture oil palm. This observation was conducted in the oil palm plantation area of PT Humusindo Makmur Sejati, Bungku Village, Bajubang District, Batanghari Regency. The infiltration rate was calculated according to the Horton method, and the amount of runoff in agroforestry and oil palm monoculture used the soil conservation service-curve number method. The results showed differences in infiltration, surface runoff, and runoff coefficients between the agroforestry land and the monoculture oil palm. The highest infiltration is in A48, which is 42,00 cm/hour in the dry season and 18,00 cm/hour in the rainy season. The lowest runoff is in A23, which is 70.14 mm with a runoff coefficient of 0.04. The highest runoff occurred in S48 of 339.88 mm, with a runoff coefficient of 0.19. The differences in infiltration, surface runoff, and runoff coefficient in this study are affected by the vegetation density and the amount of litter. Keywords: agroforestry, infiltration, oil palm, runoff coefficients, surface runoff

Optimizing rainwater harvesting systems for the dual purposes of water supply and runoff capture with study case in Bandung Area, West Java.

Rainwater harvesting (RWH) systems use runoff to meet water supply demand and may also benefit runoff reduction. We develop the Rainwater Analysis and Simulation Program (RASP) model to simulate an RWH system using storage volume, roof area, irrigated area, and water demand as inputs. A cost-benefit model of RWH was developed with subject to reliability target of water supply and runoff capture in each simulation. Near-optimal solutions were identified for each case using a constrained nonlinear programming algorithm. We apply the model to evaluate the RWH system in Bandung Area, West Java. Various types of buildings, ranging from residential houses, schools, dormitories, offices, apartments, condominiums, mosques, and hospitals, are studied to provide several optimal parameters for tank volume and number of users for various land-use scenarios. The resulting parameters are obtained through optimization to get minimal RWH’s capital costs and water purchase costs by applying several criteria related to the financial feasibility of the RWH system and by keeping the runoff coefficient not exceeding the pre-development value. The simulation results can be used as a guide for planners to consider the application of RWH in several types of buildings.

Changes in peak discharge based on sago land use scenarios in the upstream Rongkong watershed, Indonesia

Land use affects changes in peak discharge so that it has the potential to cause or prevent flooding. Sago has morphological characteristics that have the potential to absorb more water. This study aimed to determine the magnitude of the change in peak discharge in the upstream watershed after sago planting. Observations were made on the three growth phases of sago palms (initial, middle, and mature phases). The research stages included calculating the runoff coefficient value under sago stands at three growth phases. Peak discharge of the existing conditions (settlements, rice fields, mixed gardens, shrubs, sand dunes, forests, and water bodies) was estimated after three scenarios of sago land use. The scenarios consisted of 25% of the land area planted with sago (scenario 1), 50% for scenario 2, and 100% for scenario 3. The data were analyzed quantitatively by comparing peak discharge in the existing conditions with scenario results. The results showed that the peak discharge in the existing conditions was 52.36 m<sup>3 </sup>hour<sup>-1</sup>. Peak discharge in the initial phase of scenario 1 was 18.94 m<sup>3 </sup>hour<sup>-1</sup>, scenario 2 was 37.88 m<sup>3 </sup>hour<sup>-1</sup>, and scenario 3 was 75.77 m<sup>3 </sup>hour<sup>-1</sup>. Peak discharge in the middle phase of scenario 1 was 19.01 m<sup>3 </sup>hour<sup>-1</sup>, scenario 2 was 38.02 m<sup>3 </sup>hour<sup>-1</sup>, and scenario 3 was 76.04 m<sup>3 </sup>hour<sup>-1</sup>. Peak discharge in the mature phase of scenario 1 was 6.38 m<sup>3 </sup>hour, scenario 2 was 12.76 m<sup>3 </sup>hour<sup>-1</sup>, and scenario 3 was 26.55 m<sup>3 </sup>hour<sup>-1</sup>. The peak discharge in the upstream watershed decreased after the scenarios with the use of sago land for all growth phases, except for scenario 3 of the initial and middle phases.

ANALISIS PERUBAHAN PENGGUNAAN LAHAN UNTUK EVALUASI KEJADIAN BANJIR DI KOTA MANADO

This study aims to evaluate land-use changes in the city of Manado against the occurrence of floods in 2021. Analysis of land-use changes was carried out using the overlay method on maps in 2013 and 2020 with the help of GIS. The runoff coefficient value is obtained based on the land use approach by using the runoff coefficient value table to determine the relationship between land use and runoff. The results of the study show that in the period 2013–2020 there have been changes in land use that disrupt hydrological functions. Forest land, mixed gardens, and shrubs decreased by 529.83 ha (3.48%), and conversely built-up land and open land increased by 124.14 ha (0.83%) which triggered an increase in surface runoff causing flooding. The increasing fulfillment of living needs along with population growth of 34,339 people (8.18%) in 7 years requires additional land for settlement, agriculture, and supporting infrastructure. Land-use change weakens hydrological functions and contributes to increased runoff. 17% of the rainfall in 2013 and 18% in 2020 will be a runoff. Rainfall in January 2014 and January 2021 was classified as very high (>500 mm). It can be stated that the flash floods that occurred in Manado in January 2014 and 2021 were triggered by land use and high rainfall factors.

Geospatial Assessment of The Potentials of Rooftop Rainwater Harvest at The Federal University of Technology, Akure, Nigeria

Recent reports reveal water shortage at the Federal University of Technology, Akure, (FUTA), Nigeria, with possibilities to worsen if adequate measures are not taken. This research focuses on the assessment of the potential of an alternative source of water supply the Roof Top Rainwater Harvest (RTRWH) at FUTA. This study goes beyond the determination of the potential volume of RTRWH by proposing a storage plan for the RTRWH based on geospatial analysis. Data collected for the study are rainfall data covering 19 years (2000-2018), High-Resolution Satellite Image (HRSI), Ground Control Point (GCP), attribute data, Landsat 8 and Shuttle Radar Topographic Mission (SRTM) Digital Elevation Model (DEM). The rooftop areas were extracted by processing HRSI using ArcGIS software. The volumes of the RTRWH for each building were computed with the rooftop area, precipitation amount and roof's runoff coefficient of the rooftop material as variables. Suitable locations for siting the storage tanks were proposed based on Multi-Criteria Decision Making (MCDM) and geospatial analysis. Result obtained from the study reveals that the total area of rooftop catchment for all buildings considered is 164,246 m2. The study suggests 9 locations suitable for collecting and storing the harvested RTRW. The potential average daily, average monthly and total annual volumes of RTRWH are approximately 607 m3, 18,473 m3 and 221,681 m3 respectively, and thereby could potentially provide ~ 41% of water demand in addition to the existing water supply sources in FUTA. The RTRWH is therefore recommended as an alternative water source at FUTA.

Effects of post-fire mulching with straw and wood chips on soil hydrology in pine forests under Mediterranean conditions

Mulching is one of the most common post-fire management techniques, which has been widely studied at the global scale. However, more research is needed on the hydrological effects of mulching in forest ecosystems under Mediterranean semi-arid conditions. This study has evaluated water infiltration, surface runoff and soil loss using a portable rainfall simulator in Central-Eastern Spain after post-fire treatments. In this area, a large wildfire recently affected a pine forest, and the burned soil was mulched using wheat straw (dose of 0.3 kg/m2) or wood chips (2 kg/m2) on plots with two different slopes (about 30%, lower slope, and 50%, higher slope). The study has shown that the soil condition (burned control vs. soils mulched with straw or wood chips) and slope (lower vs. higher) did not significantly influence the water infiltration. However, the mean infiltration of the soils mulched with straw were higher (+40% and + 17%, respectively) compared to both the control and the plots mulched with wood chips. Moreover, lower surface runoff (−23%) was measured in the mulched soils compared to the control plots. The soil mulching with straw was more effective at decreasing the runoff coefficient (−31%) compared to plots treated with wood chips (−18%) and the control areas. Soil loss was significantly lower in plots treated using straw (−87% compared to the burned and not treated soils) compared to wood chips (−54%). Peaks of 90–95% of reduction in the soil loss were even recorded in the steeper soils. Finally, we suggest the application of wheat straw rather than wood chips, since the wheat straw mulch material provides a higher soil cover (on average 73% against 48% of wood chips) and therefore is more indicated to reduce the hydrological response in burned soils, as confirmed by the lower runoff (in the average − 16%) and erosion (−73%) measured in this experiment on both gentler and steeper soils.

Natural forest growth and human induced ecosystem disturbance influence water yield in forests

Together natural growth, afforestation and forest disturbance, such as felling, contribute to the dynamic nature of forests. Thus to enhance forest management, water resource management and carbon sequestration, the net effect of forest changes on water yield must be better understood. Here, we conduct a global meta-analysis of 496 watersheds over 25 years to investigate the impact of forest complexity and overall changes on water yields. We classify watersheds based on the type of human disturbance, including felling and thinning, afforestation, and absence of external disturbances. We find that the runoff coefficient (ratio of annual water yield in watershed outlet to precipitation) is more sensitive to external disturbances in forests with lower ecosystem complexity compared to forests with higher complexity. In addition, we found forest natural growth may increase runoff and lead to an increased runoff coefficient decades later. Our findings highlight the importance of nature-based forest restoration, especially in regions vulnerable to water shortage.

Simulation and risk assessment of typical antibiotics in the multi-media environment of the Yangtze River Estuary under tidal effect.

Frequent human activities in estuary areas lead to the release of a large number of antibiotics, which poses a great threat to human health. However, there are very limited studies about the influence of the special natural phenomena on the occurrence and migration of antibiotics in the environment. In this study, we simulated the migration and transformation of six typical antibiotics, including oxytetracycline (OTC), tetracycline (TC), norfloxacin (NOR), ofloxacin (OFX), erythromycin (ETM), and amoxicillin (AMOX), in the environmental media from 2011 to 2019 in the Yangtze River Estuary, by using the level III multi-media fugacity model combined with the factor of tides. The simulation results showed that the most antibiotics mainly existed in soil and sediment while erythromycin were found mainly in water. The concentrations of antibiotics in air, freshwater, seawater, groundwater, sediment, and soil were 10-23-10-25, 0.1-12ng/L, 0.02-7ng/L, 0.02-16ng/L, 0.1-13ng/g, and 0.1-15ng/g respectively. Sensitivity analysis showed that the degradation rate (Km) and the soil-to-water runoff coefficient (Kl) were important model parameters, indicating that hydrodynamic conditions had a significant impact on the migration of antibiotics in various environmental phases in estuarine areas. Tide can enhance the exchange between water bodies and cause the transformation of the antibiotics from freshwater to seawater and groundwater, which improved the accuracy of the model, especially the seawater and soil phase. Risk assessments showed that amoxicillin, erythromycin, ofloxacin, and norfloxacin posed a threat to the estuarine environment, but the current source of drinking water did not affect human health. Our findings suggested that, when one would like to exam the occurrence and migration of antibiotics in environment, more consideration should be given to the natural phenomena, in addition to human activities and the nature of antibiotics.

Multiple surface runoff and soil loss responses by sandstone morphologies to land-use and precipitation regimes changes in the Loess Plateau, China

In this research, a long-term (2014–2020) approach to quantify surface runoff and soil loss generated by different land use and precipitation regimes on Pisha sandstone hillslopes from the Loess Plateau, China was carried out. Using the K-means clustering algorithm, 50 precipitation events were classified into three different regime types based on depth, duration, and maximum 30-minute intensity. Permutational multivariate analysis of variance (PERMANOVA) and Principal component analysis (PCA) were used to test clustering rationality. Our results suggest that runoff coefficient (RC) and soil loss (SL) exhibited significant differences depending on precipitation regimes: heavy storms (precipitation regime II) were found to induce the largest surface runoff and soil loss, followed by precipitation regimes I and III. RC and SL were also found with significant differences (p < 0.05) related to different land-use types. Mean RC and erosion rates among the six land-use types analyzed varied as bare land > cropland > artificial grassland > native grassland > shrubland > forestland. Results of this study suggest more attention should be paid to vegetation selection and land-use type depending on precipitation regimes in Pisha sandstone morphologies. Accordingly, forestland and shrubland should be the first choices to control soil erosion when land-use conversion is implemented, whereas bare land, croplands, or artificial grassland (e.g., alfalfa) should be carefully considered and future vegetation restoration policies should assess the proper re-vegetation type before any action may be initiated.

Rainfall Runoff Balance Enhanced Model Applied to Tropical Hydrology

The integrative and comprehensive analysis considering the spatial and temporal representation of the hydrological process, such as the distribution of rainfall, land cover and land use, is a challenge for the water resources management. In tropical areas, energy availability throughout the year defines the rainfall distribution and evapotranspiration rate according to vegetation heterogeneity. To quantify water balance in tropical areas including these heterogeneities in the soil-vegetation-atmosphere relationship, we developed a fully distributed hydrological model called the Rainfall Runoff Balance Enhanced Model (RUBEM). The model was developed under a physics-based process structure, using remote sensing data to represent soil-water balance patterns, such as evapotranspiration, interception, baseflow, lateral flow, recharge, and runoff. The calibration procedure was based on nine global parameters. RUBEM could represent the spatio-temporal heterogeneities (soil, land use and land cover (LULC), topography, vegetation, and climate) in three basins in a tropical area. The results showed good adherence between the processes governing the soil-vegetation-atmosphere relationship according to the humidity indicator and the runoff coefficient. Overall, RUBEM can be used to help improve the management and planning of integrated water resources under climate, land use, and land cover changes in tropical regions.

Is Greenhouse Rainwater Harvesting Enough to Satisfy the Water Demand of Indoor Crops? Application to the Bolivian Altiplano

As many other regions worldwide, the Bolivian Altiplano has to cope with water scarcity during dry periods, which in turn impacts on crop production as flood irrigation is overwhelmingly extended in the region. Since farming is the main income in the Altiplano for most families, the availability of greenhouses with water harvesting systems may represent a solution to warrant all year round production and food access. We study the daily satisfied water demand from a balance between rainfall collected by a greenhouse roof and water used for indoor crop irrigation assuming a tank is available for water storage. This balance is analyzed for 25 greenhouses spread over Batallas Municipality, close to Titicaca Lake, Bolivia, and for two case studies: (i) using irrigation data collected from farmers in the frame of a regional project; (ii) using theoretical daily water requirements assuming an intense greenhouse farming. Our evaluation includes a sensitivity analysis of relevant parameters, such as the influence of the time window of rainfall used in the simulation, the runoff coefficient, the roof surface area, the irrigation drip system, the irrigation frequency, the crop coefficient, the volume of water used for crop irrigation, and the capacity of the water tank. Overall, we find that the runoff coefficient has little impact on the satisfied demand rate, while all other parameters can play an important role depending on the greenhouse considered. Some greenhouses are able to irrigate crops normally during the wet season, while during the dry season, greenhouses are not able to satisfy more than 50% of the theoretical water requirements, even when large tanks are considered. Based on these results, we recommend the construction of greenhouses with a ground surface of &lt;50 m2 attached to the largest available covered water tank. The information here provided can be used by stakeholders to decide their policies of investment in infrastructures in the Altiplano. Finally, the approach we follow can be applied to any other region where rainfall, temperature, and greenhouse data are available.

ESTIMATION OF WATER BALANCE OF BARSACHHU WATERSHED IN CHUKHA BHUTAN USING REMOTE SENSING AND GIS

The water balance of a watershed is critical for the estimation of the water budget to meet the present and future domestic and economic demand and supply of water. Water balance parameters like precipitation, temperature, evapotranspiration soil moisture content deficit and surplus determine the water budget of a watershed which is further influenced by factors like land use, soil types, seasonal variation and other environmental factors. This paper intends to estimate the water balance of the Barsachhu watershed using Thornthwaite and Mather (TM) model. The use of Remote Sensing data and GIS as a tool were used in deriving the required data in executing the model. The study indicates that the monthly soil moisture content (deficit or surplus) is substantially influenced by the change in monthly rainfall, temperature and land use land cover pattern. April to October remain water surplus months while November to March remains a period of deficit. The soil moisture content has a different response to different land use in the Barsachhu watershed. The maximum annual moisture deficit and surplus of the basin are 126.27 mm and 2430.79 mm respectively and is observed in built-up areas. The runoff coefficient of the Barsachhu watershed computed from the runoff simulation of the TM model is 0.63.

Impact Of Agroforestry On Hydrological Functions In The Batang Merao Hulu (Micro Watershed) Bremas District, Jambi Province

Land as a limited natural resource can suffer damage and decrease productivity if it is not managed wisely. Land use of anarea affects the hydrology of the area, changing land use means changing the type and proportion of land cover which in turn affects its hydrological response. Incompatibility of land use can have an impact on decreasing land quality, so that it often resultsin floods, droughts, erosion which will reduce land productivity and community welfare. The equipment used in this researchare: (1) Computer with ArcGIS¬ 10.4 software, ArcSWAT version 2012.1_8 Microsoft Office 2013, SWAT Plot for calculating R2and NS values; (2) Global Positioning System (GPS); (3) Digital camera, stationery and external hard disk to store data.Planting with agroforestry patterns and the application of conservation techniques in the Batang Merao Hulu sub-watershedhave an effect on hydrological characteristics, this is indicated by the reduced runoff coefficient value before plantingagrofrestry with the application of conservation techniques from 0.4 to 0.09 and the flow regime coefficient from 48.49 m3/s to 17.18 m3/s. The best land management scenario is to carry out planting with agroforestry patterns and the application of conservation techniques in the form of mound terraces. This agroforestry pattern not only emphasizes the types of woodyplants and MPTs but also prioritizes local local plants which are the prima donna of the people of Kerinci Regency, namelycoffee and cinnamon, so that ecologically, the hydrological function of the watershed is maintained.

Modular Design of Bioretention Systems for Sustainable Stormwater Management under Drivers of Urbanization and Climate Change

The increase in urbanization and climate change projections point to a worsening of floods and urban river contamination. Cities need to adopt adaptive urban drainage measures capable of mitigating these drivers of change. This study presents a practical methodology for a modular design of bioretention systems incorporating land use and climate change into existing sizing methods. Additionally, a sensitivity analysis for these methods was performed. The methodology was applied to a case study in the city of Sao Carlos, SP, Brazil. Three application scales were evaluated: property scale (PS), street scale (SS) and neighborhood scale (NS) for three temporal scenarios: current, 2015–2050 and 2050–2100. The choice of the sizing method was the factor with greatest influence on the final bioretention performance, as it considerably affected the surface areas designed, followed by the hydraulic conductivity of the filtering media. When analyzing the sensitivity of the parameters for each method, the runoff coefficient and the daily precipitation with 90% probability were identified as the most sensitive parameters. For the period 2050–2100, there was an increase of up to 2×, 2.5× and 4× in inflow for PS, SS and NS, respectively. However and despite the great uncertainty of future drivers, bioretention performance would remain almost constant in future periods due to modular design.

PENGARUH PERUBAHAN PENGGUNAAN LAHAN TERHADAP DEBIT PUNCAK DI DAS PEUSANGAN BIREUEN

The purpose of this study were to analyze and determine the magnitude of the effects of land use changes for run off coefficient and peak flows in Krueng Peusangan This study held in Krueng Peusangan, Bireuen. Land use changes in Krueng Peusangan on period 2015 - 2019 is of secondary forest decreased covers 1950 ha (2,41%), reduced mixed land farming 1241 (1,54%), ricefield 812 ha (1,00%) and the dry land agriculture 97 ha (0,12%), while the addition of comprehensive settlement of 2150 ha (2,66%), and shrubs thicket 1950 ha (2,41%) of the total area of Krueng Peusangan. Runoff coefficient value (C) increased from 0.19 in 2015 to 0.20 in 2019.&#x0D; Keyword: DAS, land use, runoff coefficient

An Analysis of the Impact of Groundwater Overdraft on Runoff Generation in the North China Plain with a Hydrological Modeling Framework

The long-term overexploitation of groundwater has caused sharp decreases in groundwater table depth and water storage in the agricultural areas of the North China Plain, which has led to obvious changes in the runoff process of the hydrological cycle, affecting the mechanism of runoff generation. Evaluating the impact of groundwater overdraft on runoff generation using hydrological models is the focus of the current work. Herein, a hydrological modeling framework is proposed based on the Variable Infiltration Capacity (VIC) model. The optimal parameters of the VIC model were determined by the synergetic calibration method, combining runoff, evaporation, and water storage levels. Meanwhile, a sliding calibration scheme was employed to explore the implied relationships among runoff coefficient, groundwater exploitation, and model parameters, particularly for the thickness of the second soil layer (i.e., parameter d2), both for the whole period and the sliding window periods. Overall, the VIC model showed good applicability in the southern Haihe river plain, as demonstrated by the low absolute value of the relative error (RE) between the simulated and observed data for runoff and evaporation, with all REs &lt; 8%, as well as large correlation coefficients (CC, all &gt; 0.8). In addition, the CCs between the simulated and the observed data for water storage were all above 0.7. The calibrated optimal parameter d2 increased as the sliding window period increased, and the average d2 gradually increased from 0.372 m to 0.415 m, for which we also found high correlations with both the groundwater table and water storage levels. Additionally, increases in the parameter d2 led to decreases in the runoff coefficient. From 2003 to 2016, the parameter d2 increased from 0.36 m to 0.42 m, and the runoff coefficient decreased by about 0.02.