International Centre for Integrated Mountain Development

This technology originated in the cold deserts west of the Indian Himalayas where underground saline water cannot be used for irrigated cultivation. This technology is also commonly used in the highlands of Balochistan (Pakistan), although with some minor modifications. A kuhl is a small water channel that is built along the hill gradient for maintaining the proper gravity flow of water. The majority of the hamlets lie on the plateaux either side of the main river, and cultivated fields are found either on naturally levelled plateaux on the banks of the rivers/torrents, or on hillside terraces. The physiographic features of the terrain restrict irrigation from rivers as they flow between steep banks. In temperate areas of cold deserts, crop cultivation without irrigation is not possible because precipitation occurs mostly in the form of snow. People have taken advantage of the glacial water to perform a collective operation for effective distribution, ensuring the supply of this scarce resource. Thus, a specialised water management technology adapted to this particular topography has been developed.

Components

Kuhl(s) (i.e., irrigation channels) are diverted from the nearest river tributaries/perennial torrents to a natural gradient so that the level of water is higher than that of cultivated fields.
In some cases, spring water is collected in small reservoirs scattered at intervals on high uplands and is drawn down to fields whenever required through kuhl(s).
Usually a spade is used for making these channels. Channels are dug in the ground to regulate the flow of water. Wherever digging is difficult or has to pass through a village track route, underground channels covered with slates are constructed. Sometimes, in this situation, wooden channels are also constructed. The wooden channels are prepared by making a deep groove in a tree trunk. Main channels are long and considerable labour is required for their annual maintenance and repair.
The whole community plays an important role in the construction of the main irrigation channels as well as in the equitable distribution of water. Usually the community works together for this purpose.
Minor channels linked to the main channel irrigate all fields.
Fields are generally divided into small compartments by using earthen bunds ( embankments) to allow water to stand in the field for a longer time for maximum water retention. The need for a second irrigation arises only after about three weeks. The process of irrigating a field is begun by flooding the nearest compartment, followed by the next, and so on. For the second irrigation, these compartments are irrigated in reverse order because irrigation is closed in that last compartment and a minor channel existed there to serve it. This process regulates proper water flow across the whole field.
Farmers ensure optimum irrigation to the desired soil depth by inserting a spade into the soil. If its blade is completely inserted into the soil, the field is considered properly irrigated. In a few locations, the irrigated soil is thrown upside down. If it splits into pieces, it is taken as a sign of a well-irrigated field.
Farmers have developed irrigation schedules matching the phenological stages of the cultivated crop (i.e., germination, vegetative, bloom, seed set, and harvest).

Since water is transported through earthen channels, it results in huge conveyance and application losses due to seepage. The irrigation efficiency is between 50 to 60 per cent. This seepage loss is not retrievable as the water level is too deep (Ahmed 1996). Similar losses occur in the case of water stored in dug-out ponds.

Spang grass is called Pang in Ladakh, where it grows profusely. Local people use this grass as an inner lining for water courses and ponds in order to prevent percolation losses. Spang grass has special non-permeable properties similar to that of a polythene sheet or cement lining. Farmers claim that its use in water retention gives far superior results than both polythene and cement. Its mysterious chemistry requires detailed analysis.

A karez is an underground, channelled irrigation system, an ancient technology that has played a historical role in the agricultural development of Balochistan, Pakistan. The history of the karez goes back thousands of years to when construction of karez systems was a hazardous and extremely specialised job. Amazingly, karez systems still exist in Balochistan. For centuries, these have been a perennial source of water for agricultural practices. Being a communal effort, water distribution rights and schedules are well settled as in the canal command areas of the Sindh and Punjab provinces of the country.

With the influx of modern technology such as tubewells, the role of the karez system is now gradually diminishing. However, this is still an important source of irrigation in the uplands of Balochistan.

Features

In a karez, lined mother wells are dug in the foothills at certain distances apart to intercept the water table high up in an alluvial fan, then water is led to the valley floor under gravity.
These mother wells are connected underground through tunnels.
A series of mother wells take water to cultivable lands. Sometimes, a karez may take perennial water flow as far as 40km.
Water is rotated from distributor to distributor and within sections of a distributor. In recent developments, concrete versions of flow dividers can be seen.

Sailaba indicates moisture conservation through flooding fields during the rainy season. Sailaba farming is extensive in most parts of Balochistan, Pakistan, particularly in the highlands. During the rainy season, flood water is harvested in catchments for crop production. This technology is extremely important in the kind of region where aridity prevails and mountain terrain accelerates water runoff. Most runoff is harvested for cultivation.

Components

Sailaba
farming involves diversion of runoff or flood water to terraced catchments for moisture conservation. These catchments are later cultivated, generally with a mixture of crops.

Farmers construct relatively level terraces, where land slope may vary between one and five per cent.

The terraces usually cover a large part of the valley and are flanked by hills on either side.

Each terrace will have an embankment at the sloping end to harvest water.

The height of the embankment varies from one to 2.5m, and the width at the top is one metre across; the lower slopes have a gradient between 2 and 2.5:1, unless the slopes are stone pitched, in which case they are vertical. Tractors and bullocks are used to make these embankments.

Flood-water channels run along a tier of terraces and bring runoff from the surrounding hills; individual terraced fields are flooded sequentially.

Two different systems are used to control the water movement from terrace to terrace.

In the first system, a stone-pitched spillway, about 2m long and 0.3 to 0.5m deep, is built at the lower left or right hand corner of the field.

In the second system, flood water flows into the field from the top corner adjacent to the water supply channel. The down-stream embankment is slightly elevated for this purpose.

The scarcity of irrigation water is a critical constraint to improved farm productivity. A standard sized water pond is an integral component of a farm's infrastructure throughout Balochistan – for the following reasons.

In Balochistan, Pakistan, irrigation methods currently followed by common farmers include the controlled flood irrigation technique on either wide border strips or basins. It is a very simple, cheap method, requiring little maintenance, yet it is also very inefficient and wastes almost 50 per cent of the precious water during conveyance from the source and by leaching from the field. Modern irrigation systems have been introduced among the more progressive farmers to control water losses and to improve the efficiency of water usage.

Trickle irrigation is most commonly micro-irrigation and involves dripping water on to the soil at very low rates (4 to 24 litres/h). It is commonly used in orchards and for vine crops, it is adaptable to any farmable slope, and is applicable to a variety of soil textures.

Components

A typical drip irrigation system is listed below.

A supply of water with adequate pressure is essential. Tubewells fitted with centrifugal electric pumps, which can pump water directly with a minimum pressure of 30 Psi at the well outlet, are the most appropriate.
The control head consists of valves to regulate discharge and pressure in the entire system. A 200 litre pressurised vessel with an inlet and outlet is used to inject soluble nutrients into irrigation water with a 140 mesh screen filter to clean water from any debris and undissolved nutrients, and it includes gauges to indicate the correct pressure of the system.
Usually a locally manufactured PVC pipe connecting different sub-mains is used as a main line.
The sub-main supplies water to the laterals on one or both sides.
The laterals supply water to the emitters - pipes laid on the ground's surface to receive water from the sub-main. Each lateral has a stopper flushing facility at the end.
Water drips from the emitters at a constant low discharge from the lateral to the atmosphere.

Tillage operations in Balochistan, Pakistan depend largely on irrigation using groundwater by tubewell, karez irrigation, and flood irrigation by spreading the flood water from hill torrents. In recent years, excessive groundwater exploitation by tubewells for irrigation, corresponding with rapid expansion of orchards, has caused considerable lowering of the groundwater table.

Simultaneously, a mismanagement of watershed areas followed by a sharp decline in vegetal cover is accelerating runoff with diminished natural groundwater recharge. To avert the risk of completely exhausting underground water resources within a few decades, delay action dams (DADs) were constructed to induce artificial recharge. DADs recharge groundwater using flood water.

Components

A DAD is constructed just within the hills where a river or creek with its flood water enters any gravelly fan.
Using modern technology to construct a huge embankment, a large reservoir is created.
This reservoir is located on river alluvium in transition to a fan.
he stored water is supposed to infiltrate and percolate to the groundwater.
Unfortunately, DADs are silting up rapidly so that the stored water tends to become finite, with water evaporating rather than infiltrating.