Water Harvesting Techniques

Water Harvesting Techniques
WHT

It is the benefiting of the scarce water that is available in short quantity in a short course of time, it is practiced in Macro-level mainly by the localities and/or the municipalities or at Micro-level which is mainly practiced by individuals or group of people trained by Non-Governmental-Organizations and the official extension workers

1. Macro-level Water Harvesting Technique

It needs a well-built infrastructure like institution, engineers, clerks, heavy machineries and strategic plan. In this technique water course must be monitored for a long time using the modern and the traditional techniques, then the institution in a very definite time is to:

1.1. Widen or narrowing the water course, or
1.2. Erect earthen dams to divert the running water to a certain direction either:
1.3. Y-shape taking water to two different directions, or
1.4. /-shape changing the direction of running water, or
1.5. Just perpendicular lines slowing down the running of water purposely to minimize its
power/speed so as to enable deep percolation or not to damage constructions ahead, or
1.6. Erecting kind of wall that prevent salt water from its ingress in to the arable area like the famous Tokar Sea Wall and at the same time keeping sweet water not to get lost

2. Micro-level Water Harvesting Technique

It is the perfect utilization of water and capturing it around the plant root zone instead of run-off, deep percolation away from the root zone and or evaporation transpiration. In some cases poor people collect rain water from the roofs into containers for drinking purpose, this technique need zinc metal roofs which is not always the case, so one need:

2.1. To minimize deep percolation and evaporation

It is the mechanical loosening of the cemented soil particles. Mainly it is practiced by farmers in their truck production holdings using tractors, or in homesteads using hoe. Sometimes farmers use intermediate technologies like Kiriako-Nubia hoe drawn by animals. This technique enable roots to absorb substantial soil moisture, at the same time this technique minimize evaporation. In some case during the soil preparation, farmers may dig 30 ~ 50 cm trenches, filled with twigs and leaves then cover with soil. Disturbing the topsoil will definitely break soil clots, while burying dead plant parts under alive root zone will provide enough moisture and compost as well.

2.2. To minimize Run-off

It is the technique in which farmers raise a crescent shape perpendicular to water runway. Normally the length of the crescent is 400 ~ 500 meter almost between 1.5 ~ 2.5 feddan area (0.5 ~ 1.0 hectare area). The height of the terrace is about 35 ~ 50 centimeter. Each terrace about 15-meter from the next one, this 15-m area will enable water to water the terrace in the backline and so forth. Due to the holding size, crops planted are easily manageable, also the terrace itself is easy to be erected. Some farmers use shovel and hoe to erect the terrace, it is an ill-advise as it is a hard job during which farmers inhale considerable amount of dust. Two farmers used to help each others using the “Urbel”. The Urbel is a reverse T-shape made from wood material, one end held by farmer some times bushing in for more depth using the body weight through his/her foot, the other farmer holding a rope fixed to the two ends of the reverse wooden pole and pulling earth up. Two farmers in two working days will finish erecting one terrace, i.e. four Mandays – if the mean offer for the manday is SDG 10.0 so the costs of erecting one terrace is SDG 40.00

Giad Sudan manufactured an excellent terrace erector called Bund Former which is drawn by a tractor, the running costs of erecting a poor farmer terrace is less than SDG 9.00. In general these kind of terraces erected in a gentle slope which is less than 7%. If the slope is acute then the terrace height must be more than the 50-cm, and the length of the terrace must be less than 400-meter, also transverse lines must exist to minimize water speed

3. WHT Benefits

3.1. Provide drinking water
3.2. Provide irrigation water
3.3. Increase groundwater recharge
3.4. Reduce seawater ingress in coastal areas
3.5. Reduce stormwater discharges, urban floods and overloading of sewage treatment
plants