Delineating Hydrological Units And Catchment And Water Ways And Water Points Under Reforestation Pdf

delineating hydrological units and catchment and water ways and water points under reforestation pdf

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This section reviews, assesses, and summarizes the potential strategies investigated in past scientific and technical research for positively affecting the watersheds and tributaries draining to Puget Sound.

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Understanding the upstream-downstream linkages in hydrological processes is essential for water resources planning in river basins. Although there are many studies of individual aspects of these processes in the Himalayan region, studies along the length of the basins are limited. This study summarizes the present state of knowledge about linkages in hydrological processes between upstream and downstream areas of river basins in the Himalayan region based on a literature review.

The paper studies the linkages between the changes in the physical environment of upstream areas land use, snow storage, and soil erosion and of climate change on the downstream water availability, flood and dry season flow, and erosion and sedimentation. It is argued that these linkages are complex due to the extreme altitudinal range associated with the young and fragile geology, extreme seasonal and spatial variation in rainfall, and diversity of anthropogenic processes.

Based on the findings, the paper concludes that integrated systems analysis is required to understand the holistic complexity of upstream-downstream linkages of hydrological processes in the river basin context. The integrated land and water resources management ILWRM approach can be instrumental in developing adaptive solutions to problems and can also enable stakeholders of upstream and downstream areas with various interests and needs to work together for the better utilization and management of land and water resources.

As a part of this, the specific circumstances of the upstream communities, who live in fragile and inaccessible mountain areas with limited resource opportunities, should be taken into account so that incentive mechanisms can be established to encourage and acknowledge their contribution.

In a river basin, hydrological events that occur in the upper part may have a direct influence downstream Nepal [ ] , from a few to many hundreds of kilometers away. Understanding these upstream-downstream linkages is an essential basis for integrated land and water resources management ILWRM and planning in a river basin. It is particularly critical in basins with extreme elevation differences, where the climatic and geological conditions at the source of the river are completely different to those downstream, and in transoundary basins, where events in one country may directly impact the situation in another Blaikie and Muldavin [ ]; Rasul [ ] ; Shrestha et al.

However, understanding such linkages is a challenge, and this is especially true in the Himalayan region Nepal [ ] , where a large, sparsely inhabited, poorly accessible, and widely glaciated area with fragile geology is the source of major rivers whose downstream basin areas are home to around one-fifth of the world's population Eriksson et al. Upstream-downstream linkages include environmental, socioeconomic, institutional, and cultural factors.

Upstream impacts on hydrological processes can be broadly divided into two types: i human-influenced activities related to land use and ii natural impacts related to climate Nepal [ ]. Various studies have looked at impacts of land use change and potential impacts of climate on hydrological regimes Chang and Franczyk [ ]; Chang [ ]; Ives and Messerli [ ]; Eriksson et al. Resource management practices in upstream areas can have both beneficial and adverse effects on downstream communities.

Good catchment management practices upstream can provide better opportunities for downstream communities, for example, a clean and sustainable water supply for irrigation. In contrast, poor catchment management practices may not only degrade upstream environmental conditions, but will also limit the opportunities downstream.

There is a general consensus that these issues are best addressed using an ILWRM approach, which promotes the coordinated development and management of water, land, and related resources GWP [ ]; Calder [ ].

ILWRM provides a basis for developing cooperation between the upstream and downstream interests, including systems to compensate upstream users for actions to benefit downstream communities. In this context, the application of alternative dispute resolution ADR for conflict resolution, as suggested by Heathcote et al.

In a small catchment, ILWRM can be based on local knowledge of interactions within the catchment, but at the larger basin level, it requires an understanding of the extended upstream-downstream linkages.

This understanding supports evidence-based decision making by providing a basis for cost-benefit analyses and thus a starting point for planning and negotiations.

This review focuses on synthesizing the available information on upstream-downstream linkages related to hydrological processes in the Himalayan region; in particular, the impacts of climate and land use changes on water quantity and sediment transport.

Specific information for the Himalayan region is limited; thus, relevant information drawn from research in other regions has also been included. Published peer-reviewed articles and technical reports on upstream-downstream linkages, impact of land use and climate change on water resources, and cooperation modalities between upstream and downstream communities were selected for the review.

Anthropogenic effects, such as construction of infrastructure, dams, and hydropower, and water extraction and pollution, also have an impact on upstream-downstream linkages in a river basin at different scales. Especially upstream, storage may have multiple purposes such as flood control, irrigation, and domestic water supply which can influence the downstream flow in many ways including timing and frequency , with reservoir management often having to prioritize conflicting purposes.

Although this issue is important, the anthropogenic aspects of upstream downstream linkages were beyond the scope of this study. Specifically, the paper focuses on reviewing evidence related to the following questions: Does change in forest cover affect hydrological flows downstream? Do forest cover and vegetation affect soil erosion and sedimentation flows? What role does upstream vegetation play in controlling downstream floods? Will climate change impact river flows and related water availability in downstream areas?

Based on the results of the literature review, the paper considers the implications for cooperation between the upstream and downstream communities, and proposes a framework based on an ILWRM approach.

The Himalayan region lies at the junction between the Indian subcontinent and Asia, and contains one of the youngest, most dynamic and fragile mountain systems in the world, with geotectonic dynamics still ongoing. The system of mountain ranges extends 3, km from Afghanistan in the west to Myanmar in the east and is sometimes referred to as the Hindu Kush Himalayan HKH region or extended Himalayan region to reflect the areas beyond the main Himalayan range Figure 1. The region contains the world's highest mountains and is the source of ten large Asian river systems Eriksson et al.

The river basins provide a source of water for drinking, irrigation, hydropower, and industry, for a population of 1. The intensity, timing, and magnitude of the monsoon precipitation vary from east to west, with the longest duration of monsoon and greatest amounts of precipitation in the east.

In the eastern part of the region, more than three-quarters of all precipitation falls during the summer monsoon months from June to September Nepal [ ] , whereas the western area receives more than one-third of total precipitation in winter Shrestha [ ].

The intense precipitation in the summer season, associated with the steep slopes and fragile geological conditions in the mountains, lead to floods and other water-related disasters like landslides that claim lives and damage property and infrastructure every year. Although events in the Himalayas have an influence far beyond the mountains, the region is data poor, and there is a marked lack of data and information especially for the high mountain areas Eriksson et al.

There are few detailed measurements of glacial ice, and the extremely poor accessibility and sparse population mean that the density of hydrometeorological stations of any sort is very low and far from being representative in a region characterized by high spatial variability of precipitation and temperature. This further compounds the problems of understanding the upstream-downstream linkages within the river basins.

In order to analyze and understand upstream-downstream linkages, river systems are broadly categorized into three distinct zones: source or headwaters zone, transition or transfer zone, and floodplain or depositional zone FISRWG [ ]; Miller and Spoolman [ ].

Figure 2 shows a conceptual longitudinal profile of a river flowing from the Himalayan mountains to the sea depicting the three main zones in profile. In the Himalayan region, the source zone or headwaters comprises the high mountains with areas of glaciers, permafrost, and snow, very steep gradients with high ridges and deep valleys, and in the highest parts, little or no vegetation.

The rivers originate in this zone within a channel network Gomi et al. Relatively high soil erosion occurs from the steep slopes, and the resultant sediment is transported downstream. The transition or transfer zone comprises the lower mountains and hills and also has steep slopes but with mixed vegetation.

Human activities such as agriculture are prevalent. The floodplain zone begins when the river leaves the hills. The river starts to meander as a result of the low gradient and the sediment transported from the upstream areas is deposited as the river passes through the floodplain.

At its mouth, the river may be divided into many channels flowing through a delta made of river-borne sediments into the sea. As the river flows from the headwaters to the floodplain, the river gains and loses water, but usually the river width and stream flow gradually increase.

The headwater systems are important for understanding and protecting downstream ecosystems because they are intimately linked Gomi et al. However, because the headwater streams are small and numerous, their roles are typically underestimated and they are poorly managed compared to the larger downstream systems.

Some processes such as glacier melt are limited to the headwater zone. Erosion, transfer, and deposition occur in all zones to some extent FISRWG [ ] , but the dominant processes generally change from erosion upstream to deposition downstream.

Thus, upstream and downstream relationships occur at different locations and scales, and the magnitude and nature of problems and related effects change between the local micro catchment scale and the regional macro river basin scale Nepal [ ].

A schematic diagram of a river corridor showing three zones and their upstream downstream relationships. Source: Miller and Spoolman [ ].

From Miller. Living in the Environment, 17E. Reproduced by permission. Physical linkages consist of numerous activities and processes that occur in upstream areas in connection with the physical environment such as land use change, runoff generation, and snow and glacier melting and their impacts on the downstream environment. There are many processes which occur simultaneously at different spatial and temporal scales and these are, by nature, complex.

Figure 3 summarizes some of the major conceptual linkages schematically. Changes in the status of the natural environment for example in climatic conditions and human systems for example resource management practices may have both qualitative and quantitative impacts on the overall hydrological regime. The current status of knowledge on the upstream-downstream linkages related to hydrology is summarized in the following; the major topics and papers reviewed are listed in Table 1.

Interacting components of upstream-downstream linkages related to the natural hydrological environment and associated human systems.

One of the major aspects of upstream-downstream linkages in terms of water is the relationship between upstream changes in land use and land cover and downstream water availability. Land use change and its impact on different aspects of the environment has been studied from both a global Watson and Verardo [ ] and regional or local perspective Awasthi et al.

Land use management practices can have both positive and negative impacts on water quantity water availability, groundwater recharge, and runoff , and water quality soil erosion, sedimentation, pollution DeFries and Eshleman [ ]. These processes and associated attributes indicate important relationships between upstream and downstream areas and developing a better understanding of the interaction between land use change and hydrological processes is a major concern in the context of sustainable water resources management DeFries and Eshleman [ ].

The potential impact of land use change on different hydrological processes has been summarized by Bronstert et al. Forests generally influence local hydrology through evapotranspiration. They also affect infiltration processes into underlying soil and ground cover through their root systems and organic humus layer, which contributes to controlling erosion dynamics.

The local climate also influences the processes by which forest and land use affect the hydrological cycle Hibbert [ ]; Wilk [ ]. The impact of land use change on average stream flow has also been investigated. Most research on forest removal in catchments has confirmed an increase in stream flow volume Douglass and Swank [ ]; Hamilton and King [ ]; Hibbert [ ]; Ives and Messerli [ ]. Hibbert [ ] investigated the effects of altering forest cover on water yield in 39 catchments worldwide.

The results suggested that forest reduction increases water yield, and reforestation decreases water yield. Bosch and Hewlett [ ] extended Hibbert's work and reviewed land use changes in an additional 55 catchments, with similar results. Several more recent studies have also indicated that a reduction in forest cover can increase water yield Andreaassian [ ], Bosch and Hewlett [ ]; Herron et al. The relationship between land use change and peak flow is also much discussed. Contrary to popular belief, upstream forests have been shown to have only a limited influence on major downstream flooding, especially large-scale events FAO, CIFOR [ ]; Ives [ ].

However, peak flows or floods can be affected by change in land use and land cover, especially when the infiltration capacity of the soil is reduced. This can occur through soil compaction or erosion, or increase in drainage capacity Bruijnzeel [ ]. As the amount of precipitation increases, the influence of soil and plant cover on stream flow generation diminishes Brooks et al.

The impact of land use on peak flow generation is less visible in a large basin because of the time-lag difference between the different tributaries and spatial and temporal variations in rainfall and land use. Although this phenomenon may reduce the effect of land use change on peak discharge in a large river basin, a sub-watershed or micro catchment may experience overall increase in peak stream flow as a result of changes in land use Brooks et al.

Gilmour et al. The study indicated that forestation of heavily grazed grasslands can lead to significant increases in surface soil infiltration capacity. The author further suggested that the measured data refute the contention that deforestation necessarily results in an increase in large-scale flooding and conversely that forestation would decrease the frequency or magnitude of such flooding. The infiltration rate is highly dependent on the antecedent soil moisture condition.

Flooding generally arises as a result of intense rainfall over a short period of time during the monsoon season, especially when the soil is already saturated and most of the rainfall is drained as runoff.

Even where forest cover is very good, such flood events remain likely. Hamilton and Pearce [ ] also concluded that reforestation might not prevent flooding to any great extent in the lower reaches of major rivers, or significantly reduce flooding during major storm events.

Global hydro-environmental sub-basin and river reach characteristics at high spatial resolution

The global burden of diarrhea is a leading cause of morbidity and mortality worldwide. In montane areas of South-East Asia such as northern Laos, recent changes in land use have induced increased runoff, soil erosion and in-stream suspended sediment loads, and potential pathogen dissemination. To our knowledge, few studies have related diarrhea incidences to catchment scale hydrological factors such as river discharge, and loads of suspended sediment and of Fecal Indicator Bacteria FIB such as Escherichia coli , together with sociological factors such as hygiene practices. We hypothesized that climate factors combined with human behavior control diarrhea incidence, either because higher rainfall, leading to higher stream discharges, suspended sediment loads and FIB counts, are associated with higher numbers of reported diarrhea cases during the rainy season, or because water shortage leads to the use of less safe water sources during the dry season. Using E.


ArcHydro and TOPAZ watershed delineation algorithms failed to unique topographic, land cover and soil attributes known as hydrologic response units (​HRUs) and water resources in the region has altered the eco-hydrology of are summarized in Table 3 for four stations located in the watersheds.


Global hydro-environmental sub-basin and river reach characteristics at high spatial resolution

Understanding the upstream-downstream linkages in hydrological processes is essential for water resources planning in river basins. Although there are many studies of individual aspects of these processes in the Himalayan region, studies along the length of the basins are limited. This study summarizes the present state of knowledge about linkages in hydrological processes between upstream and downstream areas of river basins in the Himalayan region based on a literature review.

Land use and land cover LULC change is one of the key driving elements responsible for altering the hydrology of a watershed. In this study, we investigated the spatio-temporal LULC changes between and and their impacts on the water balance of the Jhelum River Basin. The model was calibrated and validated with discharge data between and and then simulated with different land use. The increase was observed in forest, settlement and water areas during the study period.

Thank you for visiting nature. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser or turn off compatibility mode in Internet Explorer. In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. The HydroATLAS database provides a standardized compendium of descriptive hydro-environmental information for all watersheds and rivers of the world at high spatial resolution.

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Download full-text PDF WMP WATERSHEDS ABOVE SUKHI RESERVOIR (​SWAT DELINEATION) hydrology issues in watershed management in India, based on a detailed DWDU District Watershed Development Unit The starting point of the Catchment Assessment and increased cropping, tree-​planting, etc.).

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