Quantitative Assessment of Water Security Using a Hydrological Modeling Framework

Water scarcity and drought are major threats to water security. Quantifying and defining boundaries between these threats are necessary to properly assess water security of a region. A comprehensive assessment of water security in terms of water scarcity, water vulnerability and drought can address water policy issues related to hydrological conditions and their interactions with societal and ecosystem functioning. Therefore, study of water security can provide useful information to multiple stakeholders. The overarching goal of this thesis is to improve water security in river basins around the world. To demonstrate our proposed methods, we selected Savannah River Basin (SRB) as a case study. In addition to water security assessment of SRB, we also explored the combined as well as individual roles of climate, anthropogenic (e.g., urbanization, agriculture, water demand) and ecological elements on various aspects of water security. Realizing the importance of water security impacts on society and ecosystem, the following objectives are formulated: 1) To investigate the blue and green water security of Savannah River Basin by applying the water footprint concept. 2) To quantify the influence of climate variability and land use change on streamflow, ecosystem services, and water scarcity. 3) To assess the climate, catchment, and morphological variables control over hydrological drought of a river basin. To summarize, the results obtained from first objective shows that our proposed modeling framework can be applied to investigate spatio-temporal pattern of blue and green water footprints as well as water security at a county scale for SRB, thereby locating the emerging hot spots within the river basin. The results obtained from second objective indicate that the land use change and climate variability have a key influence (either concomitant or independent) in altering the blue (green) water and related water security over the basin. The results based on third objective demonstrate that in addition to climate variables, catchment and morphological properties significantly control short, medium and long-term duration of hydrological droughts in SRB. An integrated modeling framework was developed to achieve these objectives and additional findings are explained in detail through the following chapters

Cadastral level Soil and Water conservation Priority Zonation using Geospatial technology

Water is the most precious commodity that human being wanted, nowadays water is depleting due to several human interventions. In Kerala state, even though high rainfall is received, still water scarcity is faced during summer and soil erosion is higher. This watershed area is prone to water scarcity during the summer season and stream network become dry during that period. This clearly indicates that human interventions and unscientific agricultural activities may be the result. In this, study GIS and RS technologies are used to find and map the Soil and water conservation priority zones, also several action Plans where proposed. SOI Topo sheet were used to digitize the contours and DEM was created using that with ArcGIS 10.2.2 software. LULC maps were digitized from satellite image and using other parameters and suitable weight values, the weighted overlay was done to find out the Priority Zones. Cadastral Plot boundaries were overlaid for plot-wise priority zones and several conservation methods like gully plugin, check dams, vegetation bund etc. were proposed

Water Resource Management Of Simlapal Micro- Watershed Using Rs- Gis Based Universal Soil

Abstract: Water is one of the essential natural resource for the very survival of life on the planet Earth. Demand for water is increasing day by day, with the ever increasing population, resulted severe water crisis. We need water for agriculture, industry, human and cattle consumption. The available water is also affected by problem of pollution and contamination. Therefore it is very important to manage this very essential resource in a sustainable manner. Hence, we need proper management and development plan to conserve, restore or recharge water, where soil loss is very high due to various topographical conditions. The USLE (Universal Soil Loss Equation) method is one of the significant RS-GIS tools for prioritization of micro watersheds. A watershed is an ideal unit for study and to implement any model of water management towards achieving sustainable development. The significant factors for the planning and development of a watershed are its physiography, drainage, geomorphology, soil, land use/land cover and available water resources. In the current study, the micro-watershed priority fixation has been adopted under USLE model using Remote Sensing data. SRTM DEM, rainfall data and soil maps have been used to derive various thematic layers. The study area (Simlapal, W.B.) was subjected to USLE model of classifying and prioritizing the micro watersheds. The study area is divided into 22 sub-watersheds with areas ranging from 25 to 30 sq. km from the drainage map. Again each sub-watershed is divided into micro-watersheds with areas ranging from 5to10 sq. km. Thus 77 micro-watersheds were delineated for the present study area, considering all the controlling factors. Based on the results the 77 micro- watersheds could be prioritized in to five ranges viz very high, high, medium, low and very low

Salinity hazard mapping and risk assessment in the Bourke irrigation district

At no point in history have we demanded so much from our agricultural land whilst simultaneously leaving so little room for management error. Of the many possible environmental impacts from agriculture, soil and water salinisation has some of the most long-lived and deleterious effects. Despite its importance, however, land managers are often unable to make informed decisions of how to manage the risk of salinisation due to a lack of data. Furthermore, there remains no universally agreed method for salinity risk mapping. This thesis addresses these issues by investigating new methods for producing high-resolution predictions of soil salinity, soil physical properties and groundwater depth using a variety of traditional and emerging ancillary data sources. The results show that the methodologies produce accurate predictions yielding natural resource information at a scale and resolution not previously possible. Further to this, a new methodology using fuzzy logic is developed that exploits this information to produce high-resolution salinity risk maps designed to aid both agricultural and natural resource management decisions. The methodology developed represents a new and effective way of presenting salinity risk and has numerous advantages over conventional risk models. The incorporation of fuzzy logic provides a meaningful continuum of salinity risk and allows for the incorporation of uncertainty. The method also allows salinity risk to be calculated relative to any vegetation community and shows where the risk is coming from (root-zone or groundwater) allowing more appropriate management decisions to be made. The development of this methodology takes us a step closer to closing what some have called our greatest gap in agricultural knowledge. That is, our ability to manage the salinity risk at the subcatchment scale

Potential of natural groundwater recharge in the Chennai Basin with a special emphasis on the urban area

Groundwater is the primary source of drinking water in India, and the Chennai River Basin (CRB) is no exception. However, available resources of both groundwater and surface water, are constantly decreasing because of overexploitation and contamination. Well fields in the northern part of the CRB control the water supply for the region, including the Chennai Metropolitan Area (CMA), the capital of the state of Tamil Nadu. Thus, any changes in groundwater storage and availability in the basin directly affect the 11-million people who live in the CMA. So, even though the focus of this study is on the CMA, the entire basin must be considered in order to understand the hydrogeological condition and groundwater situation. This research aims to provide a holistic study of the topographic condition of the basin, the amount of water stress, the identification and mapping of the groundwater potential zones, a review of the groundwater recharge estimation techniques on national scale, and most importantly, the creation of an estimate of the natural groundwater recharge in the CRB and how climate and landuse patterns affect the recharge process. A critical review has been made of popular groundwater recharge estimation practices. The suitability of each method is found to be dependent on time-space, hydrogeological condition, and data availability. Considering the hydrogeological and climatic conditions, the Water Table Fluctuation (WTF) method is the most appropriate method of recharge estimation. Groundwater recharge is largely controlled by topographical factors such as morphometric and hypsometric analysis and understanding these factors is necessary in water resource development planning. Shuttle Radar Topographic Mission (SRTM) and Digital Elevation Model (DEM) data were used in the Geographical Information System (GIS) platform to derive the morphometry and hypsometry. The CRB is an elongated basin of the 7th order and has been classified into 11 sub-basins. Major linear, areal and relief aspects were calculated and discussed based on their hydrologic significance. Steep slopes in the basin may affect the infiltration rate and, subsequently, recharge. Hypsometric curves show the concave type for most of the sub-basins, indicating an old stage. These results provide vital information about the hydrological conditions of the basin. Protecting the resource from depletion and identifying potential zones is essential for sustainable development. Remote Sensing (RS) and GIS technologies with field data were used to map groundwater potential zones in the CRB. For the most accurate results, a total of 11 controlling factors were brought into the GIS platform and a multi-criteria decision making (MCDM) tool, Analytical Hierarchal Process (AHP), was also used. Based on this analysis, groundwater potential zones were classified into five categories- very poor, poor, moderate, good, and very good. The final groundwater potential map showed that 35% of the total area has good to very good groundwater potential, 27% has moderate potential, and 38% has poor to very poor potential. Comparison of the specific capacity obtained from borehole data with these results showed that the predicted groundwater potential identified in this study matches 80% of the area. Groundwater potential depends on climatic conditions such as droughts, atmospheric temperatures, and monsoonal patterns. Using long-term temperature and rainfall data, meteorological drought has been calculated and agricultural drought has been determined using NDVI, NDWI and VCI indices. Agricultural drought indices showed that the vegetation is healthy in the northern and southern regions. However, more than 40% of the area was found to be water stressed. The calculation was made on a decadal scale and the highest water stress was observed in the year 2010. Agricultural drought is more prominent than meteorological drought in the CRB. Chennai faces a severe water shortage in the summer season and flooding in the rainy seasons. The groundwater recharge rate for the Chennai River Basin has been estimated using the empirical method, the rainfall infiltration (RIF) technique, a GIS based distributed model, and the Water Table Fluctuation (WTF) method. The average groundwater recharge rates for different methods vary, with results of 196mm/ year (Empirical formula), 127mm/year (WTF method) and 122mm/year (RIF method). The ratio of effective recharge to rainfall is found as 10% for RIF and WTF methods and 16% using the empirical formula. Considering the conditions in India, as recommended by the Groundwater Estimation Committee (GEC), the WTF method was found to be the most reliable. Still, using multiple methods is suggested for a more fully accurate estimate. This is one of the first extensive studies that covers aspects such as terrain characteristics, proposing the most suitable groundwater recharge estimating methods, groundwater potential zone identification, water stress analysis and natural groundwater recharge estimations in the Chennai River Basin. During this study, large amount of field data on water level, atmospheric temperature, rainfall, and aquifer parameters was collected from different institutions and brought into a single scale. All this data has been brought into the GIS platform and created maps. Thus, a baseline has been created for future groundwater studies. After considering variable recharge estimates and the effective recharge ratio (approx. 10%), it is suggested that groundwater recharge be improved either by repairing existing structures or implementing artificial recharge structures based on the groundwater potential identified. This thesis contains both basic and advanced levels of scientific information, all that is necessary for policymakers to begin improvements, and even provides a number of recommendations for the most effective approach to groundwater management.Das Grundwasser stellt in Indien die wichtigste Quelle zur Gewinnung des Trinkwassers dar. Das Flusseinzugsgebiet Chennai (CRB) bildet dabei keine Ausnahme. Durch Übernutzung und Verunreinigung schwinden jedoch verfügbare Wasserressourcen, sowohl Grundwasser als auch Oberflächenwasser, stetig. Die sich im nördlichen Teil des Flussbeckens befindenden Brunnenfelder kontrollieren die Wasserversorgung der Region, einschließlich der Metropolregion Chennai (CMA) und somit der Hauptstadt des Bundesstaats Tamil Nadu. Aus diesem Grund haben jegliche Änderungen des Grundwasserspeichers und -verfügbarkeit im Flussbecken direkte Auswirkungen auf die 11 Millionen Einwohner der Metropolregion. Obwohl der Fokus dieser Arbeit auf der Metropolregion Chennai liegt, muss zum Verständnis der hydrogeologischen Verhältnisse und der Grundwassersituation das ganze Flussbeckens berücksichtigt werden. In dieser Arbeit wird eine ganzheitliche Betrachtung der topografischen Verhältnisse des Flussbeckens, der Stärke des Wasserstresses, der Bestimmung und Abbildung der möglichen Grundwasserzone, einer Überprüfung der Ermittlungsverfahren zur Grundwasserneubildung auf nationaler Ebene und, am wichtigsten, der Ermittlung der natürlichen Grundwassererneuerung im Flussbecken Chennai sowie der Weise, wie Klima- und Bodennutzungsmuster diesen Erneuerungsprozess beeinflussen, durchgeführt. Die gängigsten Praktiken zur Ermittlung der Grundwassererneuerung wurden kritisch untersucht. Es wurde festgestellt, dass die Eignung der einzelnen Methoden von den Raum- Zeit-Bedingungen, hydrogeologischen Umständen und der Datenverfügbarkeit abhängt. Bei Berücksichtigung der hydrogeologischen und klimatischen Bedingungen stellt die WTF-Methode (Water Table Fluctuation) die passendste Methode zur Ermittlung der Grundwassererneuerung dar. Die Grundwassererneuerung wird größtenteils von den topografischen Faktoren, wie der morphometrischen und hypsometrischen Analyse, bestimmt. Das Verstehen dieser Faktoren ist für die Planung der Wasserressourcenentwicklung unerlässlich. Für die Durchführung der Merphometrie und der Hypsometrie wurden SRTM- und DHM-Daten in geografische Informationssysteme (GIS) eingesetzt. Das Flusseinzugsgebiet Chennai ist ein längliches Becken der 7. Ordnung und wird in 11 Unterbecken unterteilt. Die wichtigsten Linear-, Areal- und Reliefaspekte wurden anhand ihrer hydrologischen Bedeutung berechnet und überprüft. Steilhänge in Becken können die Infiltrationsrate und somit die Grundwassererneuerung beeinflussen. Die hypsografischen Kurven der meisten Unterbecken weisen eine konkave Form vor und geben somit ihre Altersstufe an. Diese Ergebnisse bieten entscheidende Informationen über die hydrologischen Verhältnisse des Beckens. Der Schutz vor der Erschöpfung der Ressource und die Bestimmung der möglichen Zonen ist für eine nachhaltige Entwicklung unumgänglich. Die Felddaten der Fernerkundung und GIS-Technologien wurden zur Abbildung der möglichen Grundwasserzonen im FlusseinzugsgebietChennai eingesetzt. Um ein genaues Ergebnis erzielen zu können, wurden in die GIS-Plattform insgesamt 11 Kontrollfaktoren eingebracht und ein Hilfsmittel für mehrkriterielle Entscheidungen, ein analytischer Hierarchieprozess (AHP), genutzt. Aufgrund dieser Analyse wurden die möglichen Grundwasserzonen in fünf Kategorien eingeteilt: sehr schwach, schwach, mittel, gut und sehr gut. Die endgültige Karte der möglichen Grundwasserzonen zeigt, dass 35 % des Gesamtbereichs über ein gutes bis sehr gutes Grundwasserpotential, 27 % über ein mittleres Potential und 38 % über ein schwaches bis sehr schwaches Grundwasserpotential verfügen. Vergleiche der spezifischen Kapazität, die aus dem Bohrlochdaten gewonnen wurden, mit diesen Ergebnissen zeigen, dass das in dieser Arbeit vorhergesagte Grundwasserpotential zu 80% des Gebiets passt. Das Grundwasserpotential hängt von den Klimabedingungen wie Dürren, Atmosphärentemperaturen und Monsunmustern ab. Durch den Einsatz der Langzeitdaten über Temperatur und Regenfällen wurde die meteorologische Dürre berechnet, die landwirtschaftliche Dürre wurde mittels der Indexe NDVI, NDWI und VCI bestimmt. Die Indexe für die landwirtschaftliche Dürre zeigen, dass sich die Vegetation in den nördlichen und südlichen Gebieten im guten Zustand befindet. Eine Fläche von 40% des Gebiets erlebt jedoch Wasserstress. Die Berechnung erfolgte auf der dekadischen Skala, wobei der höchste Wasserstress im Jahr 2010 zu beobachten war. Im Flusseinzugsgebiet Chennai ist die landwirtschaftliche Dürre starker als die meteorologische Dürre zu spüren. In Chennai herrscht im Sommer gravierender Wassermangel, während der Regenzeit sind jedoch starke Überflutungen vorhanden. Die Grundwasserneubildungsrate für das Flussbecken Chennai wurde anhand der empirischen Methode, des Modells der Regeninfiltration (RIF), eines auf dem GIS-basierten verteilten Modells und der WTF-Methode ermittelt. Die durchschnittliche Grundwasserneubildungsrate variiert je nach Methode/Modell und zeigt die Ergebnisse von 196mm/Jahr (empirische Formel), 127mm/Jahr (WTF-Methode)und122mm/Jahr(RIF-Methode) vor. Der auf den Regen zurückgehender Anteil der effektiven Erneuerung liegt bei den Methoden RIF und WTF bei 10%, bei dem Einsatz der empirischen Formel erreicht dieser Anteil 16%. In Anbetracht der in Indien herrschenden Verhältnisse wurde die WTF-Methode, wie vom indischen Komitee für Grundwasserermittlung (GEC) empfohlen, als die zuverlässigste Methode bestimmt. Für eine möglichst genaue Ermittlung wird jedoch empfohlen, mehrere Methoden zu nutzen. Diese Arbeit gehört zu den ersten ausführlichen Studien, die sich mit Aspekten wie den Geländeeigenschaften, einer Empfehlung der geeignetsten Methoden zur Ermittlung der Grundwasserneubildung, der Bestimmung der möglichen Grundwasserzonen, der Wasserstressanalyse und der Ermittlung der natürlichen Grundwasserneubildung im Flussbecken Chennai beschäftigen. In dieser Arbeit wurde von diversen Einrichtungen eine hohe Zahl an Felddaten über den Wasserstand, Atmosphärentemperatur, Regenfälle und aquiferspezifische Parameter erworben und in einer Skala zusammengeführt. Alle diese gesammelten Daten wurden in die GIS-Plattform eingetragen und es wurden Karten erstellt. Somit wurde eine Ausgangsbasis für zukünftige Grundwasserstudien geschaffen. In Anbetracht der variablen Ermittlungswerte und des effektiven Erneuerungsanteils (etwa 10%) wird empfohlen, die Grundwasserneubildung entweder durch die Sanierung vorhandener Strukturen oder durch den Einsatz künstlicher Anreicherungsstrukturen auf der Grundlage des bestimmten Grundwasserpotentials zu verstärken. Es werden wissenschaftliche Basisinformationen vorgelegt, welche den Entscheidungsträgern zur Optimierung einer angepassten und nachhaltigen Wasserbewirtschaftung dienen können

Soil Erosion Hazard Modeling Using Remote Sensing and GIS Tool: A Case Study Namgnen Watershed in Phongsaly Province of Laos

The major factors responsible for soil erosion include factors such as rainfall, soil type, vegetation of the area, topographic and morphological characteristics. Due to the spatial variation of rainfall and catchment heterogeneity, surface erosion and sediment yield are much variable. This study is undertaken the use of empirical Universal Soil Loss Equation (USLE) with transport limiting sediment delivery (TLSD) concept to compute soil and sediment outflow in GIS environment. This involves remotely sensed and other related data for assessing the vulnerable soil erosion area within the watershed. To compute soil erosion and sediment outflow in GIS using USLE with TLSD concept, the catchment was divided into smaller grid cells of 50m x50m to account for catchment heterogeneity by considering smaller grid cell as hydrologically homogeneous area. Grid thus formed was categorized as cells lying on overland and channel areas based on channel initiation threshold in order to differentiate the processes of sediment erosion and delivery in them. In the study, GIS is used for generating representative raster layers based on various factors such as rainfall erosivity, slope length/gradient, soil erodibility and conservation practices for estimation of spatial distribution of soil erosion. In addition to this, Landsat TM imagery is utilized to produce a land use/cover map of the study area. The land use/cover map was then used in USLE model. The empirical USLE model calculates the soil loss on each cell as a function of the rainfall – runoff erosivity and the soil erodibility factors. This is then modified with the factors of topography, cover management and the support practices. The rate of sediment transport from each of the discritized cell depends upon the transport capacity of the flowing water. The eroded sediment was routed from each cell following the defined drainage path to the catchment outlet. The concept of transport limiting sediment delivery (TLSD) was used for determination of spatial distribution of transport capacity of flow within the watershed and the total sediment yield at the watershed outlet. The Normalized Difference Vegetation Index (NDVI) is used for determination of spatial distribution of transport capacity factor used in TLSD equation. Thus the total amount of sediment coming out to the outlet is the sediment yield of the catchment. The Namgnen watershed with a hydrological perspective is very significant with dense channel network of rill and gullies and significant alluvial. Further, results indicate that areas within a watersheds having high topographic factor with waste land and agricultural land and areas near first order stream produce more erosion. However, spatially computed soil removal from most of the catchment area is limited to 0-5 tons/hectare/year except few pockets which produce more sediment yield, indicating most of the areas in the catchment fall within tolerable limits of soil erosion

Identifying Suitable Watersheds across Nigeria Using Biophysical Parameters and Machine Learning Algorithms for Agri–Planning

Identifying suitable watersheds is a prerequisite to operationalizing planning interventions for agricultural development. With the help of geospatial tools, this paper identified suitable watersheds across Nigeria using biophysical parameters to aid agricultural planning. Our study included various critical thematic layers such as precipitation, temperature, slope, land-use/land-cover (LULC), soil texture, soil depth, and length of growing period, prepared and modeled on the Google Earth Engine (GEE) platform. Using expert knowledge, scores were assigned to these thematic layers, and a priority map was prepared based on the combined weighted average score. We also validated priority watersheds. For this, the study area was classified into three priority zones ranging from ‘high’ to ‘low’. Of the 277 watersheds identified, 57 fell in the high priority category, implying that they are highly favorable for interventions. This would be useful for regional-scale water resource planning for agricultural landscape development