Novel methods for scoping water harvesting sites using remote sensing products and geospatial tools.

Delaney, Robert and Folkard, Andrew and Whyatt, Duncan and Blackburn, George (2025) Novel methods for scoping water harvesting sites using remote sensing products and geospatial tools. PhD thesis, Lancaster University.

Text (2025DelaneyPhD)
2025DelaneyPhD.pdf - Published Version
Available under License Creative Commons Attribution-NonCommercial-ShareAlike.
Download (6MB)

Abstract

Water harvesting, the collection of precipitation runoff for productive purposes, offers a wide range of benefits depending on the techniques employed. It can supplement domestic water supply, recharge groundwater, enhance plant production, and mitigate erosion, among other advantages. As a result of advances in the nature and availability of remote sensing data sets, there has been significant recent growth in novel methods and tools for identifying optimal locations for specific water harvesting technologies. The work reported in this thesis makes original contributions to this ongoing growth. The substantive contributions are threefold: the ‘SiteFinder’ tool, ‘HRRTLE’ model, and a Port Sudan case study. The SiteFinder tool addresses the issue of site selection for water harvesting dams via analysis of topography. Existing approaches to site selection often emphasise slope as the primary criterion. However, such approaches tend to overlook the broader topographical context of a site, which limits their effectiveness in identifying suitable locations. SiteFinder tackles this by utilising Digital Elevation Models (DEMs) to automatically assess thousands of sites, computing parameters characterising potential dams, their catchments and impoundment reservoirs. Innovatively, SiteFinder works within a GIS environment. Thus, it allows the possibility of combining its outputs with wider multi-criteria decision-making processes. The HRRTLE (High Resolution Runoff and Transmission Loss Estimator) model is concerned with hydrological (rainfall-runoff) aspects of water harvesting prediction and site selection. Quantifying the volume of catchment runoff reaching a potential water harvesting site is crucial for assessing whether the site may face water shortages or risk its storage capacity being exceeded. Existing approaches to predicting runoff at potential sites often use curve numbers to generate runoff maps. However, they do not account for transmission losses that occur as runoff travels to a potential harvesting site across its catchment. These losses can be significant in arid and semi-arid regions where water harvesting is most common. HRRTLE addresses this issue, adding transmission loss estimates to curve number-based runoff models. The Port Sudan case study demonstrates how SiteFinder and HRRTLE can be used in combination to identify potential water harvesting sites across an area of interest. Moreover, it also introduces a novel method for optimising against the impact of sedimentation rates on storage loss in potential dam-impounded reservoirs for selected schemes. Overall, the novel tools and methodologies whose development and testing is reported in this thesis provide potential to streamline the process of water harvesting site identification, reducing the need for, and cost of, extensive ground-based work. They address topographic, hydrological and sedimentological aspects of water harvesting site selection, and provide a more comprehensive and detailed evaluation of potential water harvesting sites than existing approaches. As such, they represent novel contributions to the science of arid zone runoff prediction, and have the potential to support improved decision-making, leading to better outcomes and more efficient allocation of resources, specifically at the scoping stage of water harvesting projects.