Remote Sensing and GIS Based Approach for Identification of Artificial Recharge Sites

The main aim of this paper is to demonstrate the capabilities of Remote Sensing (RS) and Geographic Information System (GIS) techniques for the demarcation of suitable sites for artificial recharge of groundwater aquifers, in the Loni watershed, located in Unnao and Raebareli districts, Uttar Pradesh, India. In this study, the SCS-CN model, groundwater depth data and morphological parameters (bifurcation ratio, elongation ratio, drainage density, ruggedness number, relief ratio, and circulatory ratio) have been used to delineate the recharge sites for undertaking water conservation measures. Augmentation of water resource is proposed in the watershed by constructing runoff storage structures, like check dam, percolation tank and nala bund. The site suitability for these water harvesting structures is determined by considering spatially varying parameters, like runoff potential, slope, groundwater fluctuation data and morphometric information of the watershed. GIS has been used as an effective tool to store, analyse and integrate spatial and attribute information pertaining to runoff, slope, drainage, groundwater fluctuation and morphometric characteristics for such studies.     

Optimal Sites Identification for Rainwater Harvesting in Northeastern Guatemala by Analytical Hierarchy Process

The Guatemala’s rural population have limited resources, high vulnerability to climate change, traditional agriculture practices and adversely affected by water scarcity. These problems engender the need for further economic development and imposed pressure on the existing water resources. In response, Rain Water Harvest (RWH) is the measure as an alternative source towards water shortage problem and a decrease in groundwater extraction. However, the identification of optimal sites for RWH is an important step to maximize the amount of water harvested and minimize the ecological impact. In this study, an Analytical Hierarchy Process (AHP) was used to determinate optimal sites using Geographic Information Systems (GIS) in order to integrate spatial information. Physical and socio-economic features were main decision criteria along with six sub-criteria: potential runoff; land use; soil texture; slope; distance from agricultural land; and distance from roads. In the investigation, several different criteria with different AHP structures were utilized to assess the flexibility of structures. The result maps with respect to different criteria and AHP structurs are overlaid in a systematic scheme to identify the most suitable site for RWH project. The results identified four sites as optimally suitable and eight as highly suitable. The total 424,070.81 m³ volume of water can be potentially harvested from these optimally and highly suitable sites. The study area comprised of 770.61 km² of Guatemala northeastern region and it is suggested that the RWH system for agriculture purpose should be promoted through government and multistakeholder co-operations as an alternative water resource.     

Identifying Potential Rainwater Harvesting Sites of a Semi-arid, Basaltic Region of Western India, Using SCS-CN Method

Upper Karha watershed from semi-arid part of Deccan Volcanic Province, India was investigated to identify the potential sites to construct rainwater harvesting structures with the help of remote sensing and geographical information system. Attempt was made to understand the basaltic terrain in spatial context to find out the rainwater harvesting structures like farm ponds, percolation tank, check dams and gully plugs deriving from thematic layers, such as landuse/landcover, slope, soil, drainage and runoff from Landsat Thematic Mapper imagery and other collateral data. Subsequently, these layers were processed to derive runoff from Soil Conservation Service Curve Number (SCS-CN) method using Arc-CN runoff tool. The SCS-CN method shows that the high runoff potential is from water-body, agriculture land (including harvested land) and followed by settlement, open scrub, dense scrub and low for the open forest, dense forest area. Parameters like hydro-geomorphology, geology were considered as per Integrated Mission for Sustainable Development specifications for identification of the structures. The thematic layers overlaid using intersection based on these specifications. Derived sites were investigated for its suitability and implementation by ground truth field verification. In conclusion, the method adopted in present study deciphers the more precise, accurate and ability to process large catchment area than other methods.     

Application of Analytic Hierarchy Process in Water Resources Planning: A GIS Based Approach in the Identification of Suitable Site for Water Storage

One of the important objectives of water resources planning is to tap the maximum possible water available in the river basin that can be utilized particularly during the period of drought. This can be materialized by creating water storage structures. For this purpose initially, the first task could be the identification of suitable site for creating water storage sites. With the advent of Remote Sensing (RS) and Geographic Information System (GIS) techniques, it becomes easier for water resources planner to identify the suitable location of water storage structure within the basin. Present study demonstrates the identification of suitable location in the upper basin of Sheonath river in Chhattisgarh State, India. Based on the various physical characteristics of the basin, GIS based multi-criteria evaluation technique is being applied to determine the most suitable water storage sites. The suitable sites are assessed by considering the spatially varying parameters. These parameters include potential runoff, hydrologic soil group, land use, lineament, slope, stream order and settlement and basin area. Potential runoff is calculated from Soil Conservation Service Curve Number (SCS-CN) equation. Since, there is more than one parameter; it is significant to determine the importance of one layer over another layer. Analytic Hierarchy Process (AHP) is one of the multi-criteria decision making method resulting in the percentage relative importance. The AHP model consists of three levels objective i.e. suitable site for water storage, the parameter used and the alternatives. In the overlay process of GIS the relative importance determined by AHP is applied to produce suitable locations. Suitability is divided into three categories “suitability level 1”, “suitability level 2” and “suitability level 3” representing storage tank, stop dam and check dam respectively. This mapping helps in selecting potential site for water storage structures in the basin.     

Evaluation of AMC-Dependent SCS-CN-Based Models Using Watershed Characteristics

This paper presents a quantitative evaluation of the existing Soil Conservation Service Curve Number (SCS-CN) model, its variants, and the modified Mishra and Singh (MS) models for their suitability to particular land use, soil type and combination thereof using a large set of rainfall-runoff data from small to large watersheds of the U.S.A. The analysis reveals that the existing SCS-CN model is more suitable for high runoff producing agricultural watersheds than to watersheds showing pasture/range land use and sandy soils. On the other hand, the two different versions of the Mishra-Singh model are more suitable for both high and low runoff producing watersheds, but with mixed land use.     

SCS-CN Based Quantification of Potential of Rooftop Catchments and Computation of ASRC for Rainwater Harvesting

Rooftop rainwater harvesting, among other options, play a central role in addressing water security and reducing impacts on the environment. The storm or annual storm runoff coefficient (RC/ASRC) play a significant role in quantification of potential of rooftop catchments for rainwater harvesting, however, these are usually selected from generic lists available in literature. This study explores methodology/procedures based on one of the most popular and versatile hydrological model, Soil Conservation Service Curve Number (SCS-CN) (SCS 1986) and its variants, i.e., Hawkins SCS-CN (HSCS-CN) model (Hawkins et al. 2001), Michel SCS-CN (MSCS-CN) model (Michel et al. Water Resour Res 41:W02011, 2005), and Storm Water Management Model-Annual Storm Runoff Coefficient (SWMM-ASRC) (Heaney et al. 1976) and compares their performance with Central Ground Board (CGWB) (CGWB 2000) approach. It has been found that for the same amount of rainfall and same rooftop catchment area, the MSCS-CN model yields highest rooftop runoff followed by SWMM-ASRC?>?HSCS-CN?>?SCS-CN?>?CGWB. However, the SCS-CN model has close resemblance with CGWB approach followed by HSCS-CN model, SWMM-ASRC, and MSCS-CN model. ASRCs were developed using these models and it was found that MSCS-CN model has the highest value of ASRC (= 0.944) followed by SWMM-ASRC approach (=0.900), HSCS-CN model (=0.830), SCS-CN model (=0.801), and CGWB approach (=0.800). The versatility of these models lies to the fact that CN values (according to rooftop catchment characteristics) would yield rooftop runoff and therefore ASRC values based on sound hydrological perception and not just on the empiricism. The models have inherent capability to incorporate the major factors responsible for runoff production from rooftop/urban, i.e., surface characteristics, initial abstraction, and antecedent dry weather period (ADWP) for the catchments and would be better a tool for quantification rather than just using empirical runoff coefficients for the purpose.     

SCS-CN-based Continuous Simulation Model for Hydrologic Forecasting

A new lumped conceptual model based on the Soil Conservation Service Curve Number (SCS-CN) concept has been proposed in this paper for long-term hydrologic simulation and it has been tested using the data of five catchments from different climatic and geographic settings of India. When compared with the Mishra et al. (2005) model based on variable source area (VSA) concept, the proposed model performed better in all applications. Both the models however exhibited a better match between the simulated and observed runoff in high runoff producing watersheds than did in low runoff producing catchments. Using the results of the proposed model, dominant/dormant processes involved in watershed’s runoff generating mechanism have also been identified. The presented model is found useful in the continuous simulation of rainfall–runoff process in watersheds.     

Possibilities of urban flood reduction through distributed-scale rainwater harvesting

Urban flooding in Chittagong City usually occurs during the monsoon season and a rainwater harvesting(RWH) system can be used as a remedial measure. This study examines the feasibility of rain barrel RWH system at a distributed scale within an urbanized area located in the northwestern part of Chittagong City that experiences flash flooding on a regular basis. For flood modeling, the storm water management model(SWMM) was employed with rain barrel low-impact development(LID) as a flood reduction measure. The Hydrologic Engineering Center's River Analysis System(HEC-RAS) inundation model was coupled with SWMM to observe the detailed and spatial extent of flood reduction.Compared to SWMM simulated floods, the simulated inundation depth using remote sensing data and the HEC-RAS showed a reasonable match,i.e., the correlation coefficients were found to be 0.70 and 0.98, respectively. Finally, using LID, i.e., RWH, a reduction of 28.66% could be achieved for reducing flood extent. Moreover, the study showed that 10%e60% imperviousness of the subcatchment area can yield a monthly RWH potential of 0.04 e0.45 m~3 from a square meter of rooftop area. The model can be used for necessary decision making for flood reduction and to establish a distributed RWH system in the study area.     

重庆市典型下垫面 ＳＣＳ-ＣＮ模型基于坡度修正的径流曲线数优化

以重庆市渝北区和巴南区的典型下垫面为研究对象,基于ＳＣＳ-ＣＮ模型原理和坡度修正公式,通过开展人工模拟降雨实验,优化了不同植被覆盖程度的紫色土和黄壤下垫面在不同坡度（5°、10°、15°和20°）下的ＣＮ值,同时采用模型评价参数对优化前后的模型预测精度进行对比。结果表明:地形坡度变化对径流深有显著影响,地表径流深随坡度的增大大体呈现增加的趋势。同一类型下垫面的ＣＮ值随坡度的增大而增大,同一坡度下的ＣＮ值存在黄壤＞紫色土,自然草地（稀疏）＞自然草地（浓稠）。从模型评价参数来看,由Ｈｕａｎｇ坡度修正公式修正后的模型效率系数最高且平均相对误差最小。因此,在山地城市应用ＳＣＳ-ＣＮ模型时,建议使用Ｈｕａｎｇ坡度修正公式对ＣＮ值进行优化,以便更精准地预测径流。     

Identification of Potential Sites for Groundwater Recharge Using a GIS-Based Decision Support System in Jazan Region-Saudi Arabia

In arid and semi-arid environments, the amount of recharge received by aquifers is far more critical to the sustainable use of water than it is in humid regions. Groundwater recharge (GWR) is critical to maintain the abundance of groundwater. In the present study, suitable areas for GWR in Jazan region have been identified by using a GIS-based decision support system (DSS). The DSS was implemented to obtain suitability maps and to evaluate the existing GWR in the study area. The DSS inputs comprised maps of rainfall surplus, slope, potential runoff coefficient, land cover/use and soil texture. The spatial extents of GWR suitability areas were identified by a hierarchical process analysis that considered five layers. The model generated a GWR map with four categories of suitability: excellent, good, moderate and poor and unsuitable. The spatial distribution of these categories showed that 50.5 and 31 % of the study area was classified as excellent and good for GWR, respectively, while 16 and 2.5 % of the area were classified as moderate and poor and unsuitable, respectively. Most of the areas with excellent to good suitability have slopes of between 4 and 8 % and are intensively cultivated areas. The major soil type in the excellent to good areas is loamy sand, followed by silt loam, and the rainfall in these areas ranges from 100 to 270 mm. The locations of existing GWR dams were compared with the locations indicated on the generated suitability map using the proximity analysis tool in ArcGIS 10.1. Most (75 %) of the existing GWR structures that were categorised as successful were within the excellent and good areas, followed by moderately suitable (25 %).     

A Modified SCS-CN Method Incorporating Storm Duration and Antecedent Soil Moisture Estimation for Runoff Prediction

In one of the widely used methods to estimate surface runoff - Soil Conservation Service Curve Number (SCS-CN), the antecedent moisture condition (AMC) is categorized into three AMC levels causing irrational abrupt jumps in estimated runoff. A few improved SCS-CN methods have been developed to overcome several in-built inconsistencies in the soil moisture accounting (SMA) procedure that lies behind the SCS-CN method. However, these methods still inherit the structural inconsistency in the SMA procedure. In this study, a modified SCS-CN method was proposed based on the revised SMA procedure incorporating storm duration and a physical formulation for estimating antecedent soil moisture (V ₀ ). The proposed formulation for V ₀ estimation has shown a high degree of applicability in simulating the temporal pattern of soil moisture in the experimental plot. The modified method was calibrated and validated using a dataset of 189 storm-runoff events from two experimental watersheds in the Chinese Loess Plateau. The results indicated that the proposed method, which boosted the model efficiencies to 88% in both calibration and validation cases, performed better than the original SCS-CN and the Singh et al. (2015) method, a modified SCS-CN method based on SMA. The proposed method was then applied to a third watershed using the tabulated CN value and the parameters of the minimum infiltration rate (f _c ) and coefficient (β) derived for the first two watersheds. The root mean square error between the measured and predicted runoff values was improved from 6 mm to 1 mm. Moreover, the parameter sensitivity analysis indicated that the potential maximum retention (S) parameter is the most sensitive, followed by f _c . It can be concluded that the modified SCS-CN method, may predict surface runoff more accurately in the Chinese Loess Plateau.     

A Spatial Multi-Criteria Analysis Approach for Locating Suitable Sites for Construction of Subsurface Dams in Northern Pakistan

Pakistan is an agricultural country with an increasing interest for hydropower. Water management problems such as sedimentation and evaporation have been of high concern for surface water reservoirs for many years. Therefore, groundwater storage through subsurface dams could be promising, especially considering the monsoon rainfall and seasonal river flows in Pakistan. The paper aims to develop and test a methodology to locate suitable sites for construction of subsurface dams using spatial multi-criteria analysis (SMCA) in the northern parts of Pakistan. For the study, spatial data on geology, slope, land cover, soil depth and topographic wetness index (TWI) was used. Two weighting techniques, i.e. the analytic hierarchy process (AHP) and the factor interaction method (FIM), were employed and compared. The sensitivity of the two methods as well as of the model parameters was analysed. The suitability map derived from AHP yielded about 3 % (16 km²) of the total area as most suitable, about 4 % (22 km²) as moderately suitable and about 0.8 % (5 km²) as least suitable. The suitability map derived from FIM identified about 2.7 % (14 km²) of the total area as most suitable, about 4 % (22 km²) as moderately suitable and about 1 % (7 km²) as least suitable. The sensitivity analyses suggested that AHP was a more robust weighting technique than FIM and that land cover was the most sensitive factor. The methodology presented here shows promising results and could be used in early planning to locate suitable sites for construction of subsurface dams.     

An Event-Based Sediment Yield and Runoff Modeling Using Soil Moisture Balance/Budgeting (SMB) Method

Water Resources Management - The Soil Conservation Service Curve Number (SCS-CN) method is frequently used for the estimation of direct surface runoff depth from the small watersheds. Coupling the...     

Modeling the Effect of Cistern Size,Soil Type,and Irrigation Scheduling on Rainwater Harvesting as a Stormwater Control Measure

Urban stormwater runoff could have negative impacts on water resources and the environment. Rainwater Harvesting (RWH) can serve both as a stormwater control and water conservation measure. Cistern size and irrigation scheduling are two of the factors that directly impact the total runoff from a residential unit with a RWH system and the amount of potable water used for irrigation. The effectiveness of RWH was evaluated for four soil types; Sand, Sandy Loam, Loamy Sand, and Silty Clay, with a root zone of 15.2 cm using three irrigation scheduling methods (Evapotranspiration (ET)-based, soil moisture-based, and time-based), and five cistern sizes. Total runoff volumes and total supplemental potable water used were compared among the three irrigation scheduling systems and a control treatment without RWH. A model was developed to simulate the daily water balance for the treatments. Irrigation and runoff volumes were compared for the various scenarios. Silty clay soil resulted with 83 % more runoff than Sandy soil, while Sandy soil required on average 58 % more supplemental water than Silty Clay soil. On average, the 833 L cistern resulted with 41 % savings in water supply and 45 % reduction in total runoff. Results showed that the greatest volumes of runoff predicted were for the silty clay soil Control Treatment using a time-based irrigation scheduling method, while the least volumes calculated were for the sandy loam soil time-based irrigation scheduling treatment with 833 L cistern size. The greatest volumes of total supplemental water predicted were for sandy loam soil Control Treatment, while the least volumes were for silty clay soil ET-based irrigation scheduling treatment with 833 L cistern size. Regression equations were developed to allow for users to select a RWH cistern size based on the amount of water they want to save or runoff to reduce.     

Policies and Strategies to Overcome Barriers to Rainwater Harvesting for Urban Use in Ethiopia

The Ethiopian government has been working on rainwater harvesting (RWH) for more than three decades. Despite its efforts, the results are not as expected. Different barriers have posed challenges to promoting RWH in Ethiopia. This study was done to identify the main problems and obstacles, and reflect on potential solutions. As a result, absence of clear policy definitions, lack of sustainably implemented projects, poor societal perceptions of RWH, local professionals lacking proper knowledge, and initial investment costs are found to be major causes of poor outcomes. Considering the site-specific nature of water issues, the authors propose various management strategies such as policy-oriented promotion, formulation of design guidelines, proactive planning, collaborative research, and integration of RWH with cost covering practices.     

Application of GIS-based SCS-CN method in West Bank catchments,Palestine

Among the most basic challenges of hydrology are the prediction and quantification of catchment surface runoff.The runoff curve number(CN)is a key factor in determining runoff in the SCS(Soil Conservation Service)based hydrologic modeling method.The traditional SCS-CN method for calculating the composite curve number is very tedious and consumes a major portion of the hydrologic modeling time.Therefore,geographic information systems(GIS)are now being used in combination with the SCS-CN method.This paper assesses the modeling of flow in West Bank catchments using the GIS-based SCS-CN method.The West Bank,Palestine,is characterized as an arid to semi-arid region with annual rainfall depths ranging between 100 mm in the vicinity of the Jordan River to 700 mm in the mountains extending across the central parts of the region.The estimated composite curve number for the entire West Bank is about 50 assuming dry conditions.This paper clearly demonstrates that the integration of GIS with the SCS-CN method provides a powerful tool for estimating runoff volumes in West Bank catchments,representing arid to semi-arid catchments of Palestine.     

GIS-based Methodology for Identification of Suitable Locations for Rainwater Harvesting Structures

Presently, the water resources across the world are being continuously depleted. It is essential to find sustainable solutions for this shortage of water. Rainwater harvesting is one such promising solution to this problem. This paper presents a new GIS-based methodology to identify suitable locations for rainwater harvesting structures using only freely available imageries/remote sensing data and data from other sources. The methodology has been developed for the semi-arid environment of Khushkhera-Bhiwadi-Neemrana Investment Region (KBNIR) in Alwar district of Rajasthan. For identifying locations suitable for rainwater harvesting structures, the layers of surface elevation (ASTER-DEM), landuse/landcover, soil map, drainage map and depression map are used and further analyzed for their depression volume, and availability of surface runoff using Soil Conservation Service - Curve Number (SCS-CN) method. Based on the proposed criteria total seven locations were identified, out of which two locations are excellent; three locations are good, (if provisions of overflow structure are made for them) and two locations are not suitable for rain water harvesting. The total rainwater harvesting potential of the study area is 54.49 million cubic meters which is sufficient to meet the water requirements if harvested and conserved properly. This methodology is time-saving and cost-effective. It can minimize cost of earthwork and can be utilized for the planning of cost effective water resource management.     

Rainwater harvesting and poverty alleviation: a case study in Gansu,China

China faces great challenges to alleviate poverty as it enters the new century. There are still 30 million people living below the absolute poverty line. They are concentrated in the mountainous areas of western China, of which the loess area of Gansu province is one of the driest and poorest. One of the root causes of poverty is water scarcity. Water is the key factor in changing the fundamental conditions for the existence and development of the poor areas. Due to the topographical nature of the area, a major water delivery project would be difficult to build and be economically unfeasible. The most easy-to-use water source with the highest potential is rainwater. Rainwater harvesting (RWH) has been carried out in previous decades and it has been shown that it can serve the poor by supplying water for domestic use and supplemental irrigation, thus ensuring both water and food security. It can create a pre-condition for the modification of agricultural structure, thus promoting income generation. RWH is also beneficial to the recovery of the ecosystem and environmental conservation in the semi-arid northwest region of China. Past experiences show that RWH is an innovative approach for the integrated and sustainable development of the poor areas. It is reasonable to mainstream RWH in integrated water resources management.     

Assessment of flood regulation service based on source–sink landscape analysis in urbanized watershed

Facing climate change and rapid urbanization, urban flooding has exposed human and properties to increasing disaster risks. The attention from researchers and decision-makers to understand the key role of flood regulation service (FRS) in flood management has arisen. However, the mechanism of FRS supply–demand is little known from landscape scale. The FRS assessment methodology considering interacts between source, sink, and flow landscape was proposed in this study. The spatial distributions of surface runoff generation, runoff reduction capacity, and flood inundation were mapped using one-dimensional rainfall–runoff method SCS-CN and two-dimensional flood propagation model CADDIES. Four 3-hour designed rainfall scenarios ranging from nuisance to extreme events (3a, 11a, 56a, and 100a) were simulated. The Liuyang River Watershed in Changsha Municipality, China was selected for case study. The results showed that, the differences of runoff reduction coefficient and runoff generation volume between vegetation and built-up landscape have shortened. The peak flood depth, extent of flood inundation, and peak flood velocity have increased continuously with the growing rainfall intensity. The number of source–sink mismatch catchment was the highest under 56 and 100a, and the most of source-sink match catchments were observed under 3a. Under four rainfall scenarios, the changes of source–sink relationships were witnessed and the potentials of flow zone in source–sink mismatch catchments have increased. The FRS management framework concerning supply–demand connections has been proposed based on source–sink–flow analysis. These findings could provide a scientific basis for sustainable urban flood management and disaster risk mitigation.     

Evaluating Retention Capacity of Infiltration Rain Gardens and Their Potential Effect on Urban Stormwater Management in the Sub-Humid Loess Region of China

Recognized as an effective low impact development (LID) practice, rain gardens have been widely advocated to be built with urban landscaping for stormwater runoff reduction through the retention and infiltration processes; but the field performance and regional effect of rain gardens have not been thoroughly investigated. In this paper, we presented a four-year monitoring study on the performance of a rain garden on stormwater retention; hydrological models were proposed to predict the potential effect of rain gardens on runoff reduction under different storms and the future urban development scenarios. The experimental rain garden was constructed in a sub-humid loess region in Xi’an, China; it has a contributing area ratio of 20:1 and depth of 15 cm. During the study period, we observed 28 large storm events, but only 5 of them caused overflow from the rain garden. The flow reduction rate for the overflow events ranged from 77 to 94 %. The runoff coefficient from the contributing area (RC) was reduced to less than 0.02 on annual basis, and 0.008 over the four years average. Field observations also showed that infiltration rate remained stable during the operation period. The predictions based on the future landuse and storm variability of the study area showed that by converting a small fraction of the city land area into rain gardens, the negative hydrological effect from expansion of impervious area can be reduced significantly. The challenge, however, lies in how to plan and build rain gardens as an integral part of the urban landscape.