University of Twente Student Theses


Soil salinization on the floodplains of the Lower Shire River

Velema, Jorick (2008) Soil salinization on the floodplains of the Lower Shire River.

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Abstract:The floodplains of the Lower Shire River are one of the seventeen major floodplains in Africa and directly benefit an estimated 1 million people in riparian communities in Malawi and Mozambique. Certain areas of the floodplains exposed to flooding are experiencing soil salinization. Objective of the research is to determine if the soil salinization is caused by flooding or by capillary action, by performing a literature study and setting up a 1D soil water model. Malawi is a land-locked country located in south-east Africa lying along a sector of the East African Rift. The biggest lake, Lake Malawi, drains freely into the Indian Ocean through the Shire River then the Zambezi. The Shire River is the only outlet from Lake Malawi from which it meanders southwards for a distance of approximately 700 km to its confluence with the Zambezi River. The floodplains of the Lower Shire River studied in the research floods every year when the water level in the Shire River rises. After the floods water stays behind on the floodplains which infiltrates and evaporates. Under the floodplains are two aquifers. A unconfined saline aquifer (3779 mg/L sodium) with a groundwater level of 0,5 m and a confined fresh water aquifer starting at 20m below surface. The climate of the Lower Shire Valley is characterized by two well-defined seasons; the hot-dry season from May to October, and the warm-wet season from November to April. The precipitation is 788mm/year and the evaporation is 2080mm/year making the valley evaporation dominated. To study to the soil salinization, the different processes that influence the soil salinization are simulated in a 1D numerical model. Any process that affects the soil-water balance may affect the movement and accumulation of salts in the soil. These processes include; hydrology, climate, irrigation, drainage, plant cover and rooting characteristics, farming practices. Two possible soil salinization processes might occur. This is soil salinization due to flooding and soil salinization due to capillary rise.
Item Type:Essay (Bachelor)
Faculty:ET: Engineering Technology
Subject:56 civil engineering
Programme:Civil Engineering BSc (56952)
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