Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Accueil du site → Doctorat → Pays-Bas → Water Resources Strategies to increase Food Production in the Semi-Arid Tropics : With particular emphases on the potential of alluvial groundwater

TU Delft, Delft University of Technology (2013)

Water Resources Strategies to increase Food Production in the Semi-Arid Tropics : With particular emphases on the potential of alluvial groundwater

Love, D.

Titre : Water Resources Strategies to increase Food Production in the Semi-Arid Tropics : With particular emphases on the potential of alluvial groundwater

Auteur : Love, D.

Université de soutenance : TU Delft, Delft University of Technology

Grade : Doctoral thesis 2013

Résumé partiel
A number of hydroclimatic and institutional factors converge to emphasise the need for investment in water management and water resources modelling in southern Africa. Water demand continues to rise, as urban areas expand and as agricultural water demand rises to meet the millennium development food security goals. In average years, water demand (principally from agriculture and urban areas) is in a precarious balance with available water resources, with major deficits and severe food insecurity being recorded during droughts. Access to water is limited by actual scarcity, availability and affordability of water storage and appropriate abstraction technology and water allocation practices. This study shows that water resource availability in the northern Limpopo River Basin (i.e. the portion of the Limpopo Basin located in Zimbabwe, also known as the Mzingwane Catchment) has declined over the last 30 years, both in terms of total annual water available for storage (i.e. declines in annual rainfall, annual runoff) and in terms of the frequency of water availability (i.e. declines in number of rainy days, increases in dry spells, increases in days without flow). Furthermore, a number of climate change models predict that southern Africa shall experience significantly reduced precipitation and runoff over the next fifty years. Simulation modeling suggests a more than proportional decline in runoff and water for productive use. Changes in water and land use strategies can have significant effects on water resources. Increases in irrigation, and construction of reservoirs, have obvious effects on river systems, but rainfed agriculture and land use changes, whilst not necessarily exhibiting demand for surface or groundwater, can exert a strong influence on runoff generation. In this context, there is a clear requirement for water resources modelling to support integrated water resources management planning in order to balance food security, other economic needs and the needs of the environment in the allocation and development of blue water flows. This study seeks to model water resources at river basin scale in order to quantify the effect of different water and land use strategies and hydrological and climatic conditions on water resources availability. An extended version of the HBV light rainfall-runoff model was developed (designated HBVx), introducing an interception storage and with all routines run in semi-distributed mode via visual basic macros in a spreadsheet. This was used to characterise the response of meso-catchments in the study area to rainfall, in terms of the production of runoff vs. the interception, transpiration and evaporation of water. This is important in small semi-arid catchments, where a few intense rainfall events may generate much of the season’s runoff. HBVx was regionalised across 19 meso-catchments and satisfactorily models the ephemeral surface flow and the minimal baseflow from deep groundwater in semi-arid meso-catchments. Mesocatchments in the study area are characterised by high levels of interception, slow infiltration and percolation and moderate to fast overland flow

Présentation

Version intégrale (11 Mb)

Page publiée le 27 décembre 2014, mise à jour le 2 janvier 2018