Phd thesis on rainwater harvesting

Phd thesis on rainwater harvesting

We will not breach university or college Phd Thesis On Rainwater Harvesting academic Phd Thesis On Rainwater Harvesting integrity policies. Disclaimer: nascent-minds is Phd Thesis On Rainwater Harvesting dedicated to Phd Thesis On Rainwater Harvesting providing an ethical tutoring service/10() Without a doubt, a dissertation is one of the most important and hard-to-write papers. But we are able to lift this enormous burden from your shoulders by crafting a thoroughly researched and Rainwater Harvesting Phd Thesis well-written dissertation for you/10() If a customer feels somewhat Phd Thesis On Rainwater Harvesting dissatisfied with Phd Thesis On Rainwater Harvesting their paper, they are welcome to ask the writer to make necessary changes. Then, writers will revise the paper as many times as it is required for customers to be fully pleased with Phd Thesis On Rainwater Harvesting their orders/10()

Phd Thesis On Rainwater Harvesting

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Remember me on this computer. Enter the email address you signed up with and we'll email you a reset link, phd thesis on rainwater harvesting. Need an account? Click here to sign up. Download Free PDF. Rainwater harvesting using dead level contours and infiltration pits under semi-arid conditions in Zimbabwe.

Walter Mupangwa. Download PDF Download Full PDF Package This paper. A short summary of this paper. Rainwater harvesting using dead level contours and infiltration pits under semi-arid conditions in Zimbabwe W. Twomlow 2, S. com or w. mupangwa cgiar, phd thesis on rainwater harvesting. org 2 United Nations Environment Programme, P O BoxNairobi, Kenya 3 Department of Soil, Crop and Climate Sciences, University of Free State, Bloemfontein, South Africa Abstract The persistent droughts and in-season dry spells, phd thesis on rainwater harvesting, and chronic food insecurity in semi-arid areas necessitate the introduction of more robust rainwater harvesting and soil water management technologies.

It is rare for drought or in-season dry spells not occur during the growing season in semi-arid parts of Zimbabwe, phd thesis on rainwater harvesting. The current study was conducted to assess the influence of dead level contours and infiltration pits on in-field soil water dynamics over two growing seasons. The study was conducted at four farms, two farms having dead level contours only while the other two farms had dead level contours and infiltration pits located along the contour.

A transect consisting of six access phd thesis on rainwater harvesting, spaced at 5 m interval, was established across each dead level contour with or without an infiltration pit before the onset of the rains. Two access tubes were installed upslope of the contour while four tubes were installed on the downslope side. Dead level contours with infiltration pits captured more rainwater than dead level contours only resulting in more lateral soil water movement.

Significant lateral soil water movement was detected at 3 m downslope following rainfall events of mm. The 0. This is not practical given the high labour demand and the limited crop yield benefits derived from having these structures on the field. It is probably worth exploring strip cropping of food and fodder crops on the downslope of the dead level contours and infiltration pits.

Key words: Dead level contour, infiltration pit, rainwater harvesting, semi-arid, Zimbabwe 1. Introduction Rainfed crop production plays a pivotal role in the developing countries where the majority of the people depend on agriculture for their livelihoods Verchot and Cooper, In the Southern African Development Community SADC region human population is growing at 2.

The decrease in crop output from the smallholder farming sector is related to climatic and socio-economic constraints. Rainfall is the major climatic factor that influences crop production in the smallholder sector under semi-arid environments Thomas et al. Rainstorms are often spatially distributed, varying highly even within a few square kilometres Usman and Reason, ; Masvaya, et al.

These rainfall characteristics are likely to continue haunting the smallholder agricultural sector of sub-Saharan Africa in the face of climate change. The African continent has been identified as one part of the world to be hit hard by climate change Jones and Thornton, Rainwater harvesting, a method of collecting surface runoff phd thesis on rainwater harvesting a catchment area and storing the water in the root zone of a cultivated area for crop growth Li et al.

In the semi-arid areas rainwater harvesting could be a source of water for smallholder cropping systems Falkenmark et al. Traditionally smallholder farmers in Zimbabwe have been using the graded contour ridge for safely diverting excess water from the field AGRITEX, undated; Mutekwa and Kusangaya, A standard graded contour ridge is pegged at a gradient of and contour ridges are usually spaced at 20 to 30 m apart on gentle slopes AGRITEX, undated; Hughes and Venema, Dead level contours, pegged at zero gradient, are an appropriate between-field technique for harvesting runoff water for crop production.

The purpose of a dead level contour is to retain runoff water in the contour hoping that soil water will move into cropped field by lateral flow Hughes and Venema, To improve the ability of the dead level contour in retaining runoff, water infiltration pits are dug along the contour often at 10 m interval AGRITEX, undated. A standard infiltration pit measures 2 m long, 1 m wide and 0. Phd thesis on rainwater harvesting Gwanda district of southern Zimbabwe dead level contours and infiltration pits are being promoted by Practical Action Southern Africa.

The design of the dead level contours includes having an infiltration pit at intervals along the contour. Dead level contours and infiltration pits have been explored in other semi-arid districts of Zimbabwe Motsi et al. Results from these studies have shown that dead level contours and infiltration pits can contribute towards soil water status in the cropped field. In a study by Mugabe rainwater captured by the infiltration pits replenished soil water on the upslope and downslope sides of the infiltration pit, phd thesis on rainwater harvesting.

Our study in Gwanda district was designed to assess the influence of dead level contours and infiltration pits on soil water patterns on the upslope and downslope sides of dead level contours with or without infiltration pits.

The specific objectives of the study were 1 to measure the profile soil water content at 7 and 2 m upslope, and at 3, phd thesis on rainwater harvesting, 8, 13 and 18 m downslope of the dead level contours with and without infiltration pits throughout the growing season and 2 to determine the extent to which soil water moves laterally from contours into the cropped field.

This paper reports on the soil water changes observed at 2 and 7 m upslope and 3 and 8 m downslope of the dead level contours. Materials and methods 2. Site description Gwanda district is lies in the Mzingwane catchment which is part of the Limpopo river basin and receives annual rainfall of less than mm Unganai, ; FAO, The cropping season experiences periodic dry spells particularly in January and is followed by a dry season that stretches from May to September.

The predominant soils in Gwanda district are coarse-grained sands to loamy sands and clay loams to clay with minor occurrences of vertisols Anderson et al. Experimental set up The experiment was established at four farms located in ward 17 of Gwanda district, southern Zimbabwe.

Two farms Moyo and Ncube had dead level contours only while the other two Dube and Siziba had dead level contours and infiltration pits Plate 1. The access tubes were sunk to depths varying from 0. Depth of access tubes was restricted by the presence of a stony layer in the profile at three of the four farms. At each farm access tubes were installed in October and maintained for the subsequent seasons.

The dead level contours averaged 0. The infiltration pits averaged a b Plate 1. Schematic diagram of the set up of access tubes across dead level contours at each farm in Gwanda phd thesis on rainwater harvesting 2. Soil water was measured fortnightly at 0. Six to eight readings were taken from each access tube depending on the depth of the access tubes. Soil water content in millimetres was determined by multiplying volumetric water content by the thickness of each layer where the soil water was measured.

The soil water content in the Soil samples were collected at 0. Soil water data analysis Soil water data were analyzed using the method of residual maximum likelihood REML in Genstat version 9.

In the analysis of soil water data the following model was applied; 2. Depth Random model: Farm 2. Results and Discussion 3, phd thesis on rainwater harvesting. Soil physical properties at the four farms The physical properties of the soils at the four farms used in this study are summarized in Table 1. Coincidentally the farms that had a dead level contour with infiltration pits had higher clay content in the soil profile than those with dead level contours only.

The soil types at the four farms ranged from sand to loamy sand. Table 1. Seasonal rainfall at the farms 3. A day dry spell was experienced from 2 January day 94 to 26 February day when 22 mm of rain was received.

The dry spell coincided with the vegetative and flowering stages of the major cereal crops maize, sorghum and pearl millet resulting in complete crop failure on most smallholder farms in Gwanda district.

Dry spells occurring during the cropping period are a characteristic feature of semi-arid areas of East Africa Barron et al. Most of the rainfall events were concentrated in the October to December period with just five events occurring during the January to April period.

The highest daily rainfall event was 70 mm recorded on 8 January day at Dube, phd thesis on rainwater harvesting, Moyo and Ncube farms.

The last rainfall event was recorded on 24 January day with 18 to 20 mm being received across the four farms. Soil water changes in fields with dead level contours only 3.

The lowest profile water content was recorded at 7 m upslope of the dead level contour throughout the season. The phd thesis on rainwater harvesting in profile water content between these two dates is attributed to soil water uptake by crops growing around the access tubes as well soil evaporation. In the A 7 mm rainfall event was recorded at Moyo farm between 25 January day and 19 February day and this amount was negligible to cause any notable changes in profile soil water phd thesis on rainwater harvesting. The soil profiles phd thesis on rainwater harvesting Moyo and Ncube farms were recharged by mm of rain that was received between 28 March days and 13 April Figs.

The 0—0. There was higher soil water content at 8 m from the dead level contour than other distances suggesting the contribution of conventional ploughing to the measured soil water. In the top 0. After receiving 70 mm of rain, the highest profile water content along the ploughed transect was recorded at 3 m downslope, suggesting that water had moved laterally from the dead level contour.

Conventional ploughing further increased profile water content along the ploughed transect. Ploughing loosens the soil and creates surface depressions that collect rainwater giving it more time to infiltrate Van der Meer, phd thesis on rainwater harvesting, ; Sasal et al.

Along the unploughed and ploughed transects the 0—0. The highest soil water content at each soil depth was recorded at 3 m along the unploughed transect Fig.

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