PAKISTAN comes under the arid and semi-arid zones of the world. In these areas precipitation pattern is decling day by day. Drought, desertification and water shortage are the main indicators of the changing environment.It is widely believed that water distribution could be the main cause of any future war.

Irrigation experts are of view that there could be two approaches to the problem: judicious distribution of water at the system level and the second could be the site specific water resource management. The need of the hour is to plan the site specific water resource management in the water-scarce areas and to develop new water saving devices for fertile belts.

In the Sindh province, the fertile lands are in the Indus basin, irrigated through canal system and others in the ‘kacha’ belt of district Dadu having no canal irrigation system, and which mainly depends upon rainfall and irrigation through hill torrent’s runoff. The average annual rainfall in ‘kacha’ area is about 4.75 inches and the rainfall frequency is also not constant. So only the crops needing single irrigation such as jowar, guar, mustard and sesame could be grown.

June July and August are considered as wet months of the year. But since 1996 there has beens no rainfall in these months except in the monsoon season of 2001. In this situation, the second source could be the torrential run-off water in the form of flood.

Water flows through hills comes from far-off parts of Khirthar mountain range, which is locally known as ‘Nais’ (water courses). The main hill torrents that enter in the ‘kutcha’ area are Gaj Nai, Naing Nai, Angai Nai, Taki Nai, Nali Nai, Shori Nai and Gar Nai. All these water courses ultimately reach the Manchar Lake.

At the entrance point of Gaj Nai into ‘kachha’ area, a wall along side a stone mound is constructed locally called Teer Bhit. The first Teer Bhit constructed in 1934 and was destroyed during the flood of 1995 which was constructed again in 1996. The following are the details of the nine channels taking of at Heer Bhit:

Earthen hack structures: It is an obstacle (mound) that restricts or checks the flow. At Sol Nai, about three earthen check structures remain in place which are locally called Kanday Jo Gandho. These check structures may be breached during heavy floods. When flows are nominal, it could be stored by the first check structure. When it has flooded the adjacent lands, an artificial breach is made in the earthen check structure to provide water to the next check structure.

These days, Kando Babbar check structure is not so economical while other two are more economical and hence have been re-built time and again.

The earthen check structure at Sole Nai situated near village Bahawal Babbar is about 23 km in the West of Johi. This check structure is in place for many years. In the year 1999 it was constructed twice and both times it was breached due to hill torrent’s run-off.

The earthen check structure’s idea is quite old but there are no organised efforts to built such checks. During the 2001 monsoon season, the Bahawal jo Gandho breached due to Gaj Nai flood as a result of which huge losses were incurred by farmers.

Channel system: The Sole Nai and off-taking channels are not man-made. These are natural waterways made by water run-off erosion. With the passage of time, these channels, which were in direct approach of huge flows with erosive velocities, became wider and deepened.

Just up stream of the earthen check structure at Bahawal Babbar, two channels taking off from it. Pathan Wah taking off on its right side and Chidi Wah taking off on its left side. About 4-8 branch channels also take off from both channels. All the channels and branch channels are natural waterways.

Wakra (small earthen check structures) are developed just down stream from take-off points of each branch channel for diverting flow in the first branch channel, that is to some extent elevated from others. While few other Wakra have been developed with respect to land elevation at different reaches from head to tail of the branch canal for irrigating the lands with respect to elevation in reaches.

Water availability: During a survey undertaken in August 2000, at the upstream of the earthen check structure, the water was stored. It’s backwater effect observed in the range of more than 10 km with the depth of 4 to 10 feet and about 1200 to 1600 feet in width. The water level in the Sole Nai was about 20-ft blow the ground surface. In other words, it could be said that about 321 million cubic feet water was stored in the system. If supply provided to lands with the rate of 41.33 cusecs for three months, every crop could be harvested at the 12401 acres of land. This amount of water was available since last one and half months and will remain for one and half month in the Nai. Since one and half month water lifting machines were lifting the water for irrigation.

This amount of water came in different flows during June to August. It was noted during survey that about 15 to 20 flows came annually in an average depth of 4 to 8 feet, without any rainfall in Kachho area. Last four years since 1996 were the dry years but in the months of June, July and August water flows came in the Nai every year.From the Teer Bit about 10 cusecs flow remains more or less for the whole year.

In case of hill torrent flows, if there is no earthen check structure at Nai, all the water rushed to the Manchar Lake. It mixed with Manchar’s polluted water and ultimately drains off into Indus River through Danistar and Arral canals. This run-off destrys the chance of using water for irrigation as well as drinking for Kachho area and also reduces the possibility of recharging the ground water aquifer. Sudden and high velocities erode the bed and banks of the Nai. Near Kando Babar many villages were damaged by Nai due to erosion.

Local distribution system: Locally,irrigation regulation is based on bulk distribution (Warabandi) system. This followed the construction of comparatively small check structures (Wakra) at the downstream of branch channel to divert the flow of the main channel. After irrigating the command area of the first channel, the Wakro is artificially breached by landowners having land along the second channel . In this way all the secondary channels get water one by one.

When water level is not enough to irrigate gravitationally, the water is lifted through lift pumps. About 35-40 lift pumps were continuously lifting water for irrigating adjacent lands at the upstream of earthen check structure at Sole Nai. These pumps are used by people who can afford them and who had contributed in the construction of earthen check structure (Gando).

Land management: Land management has been done according to the irrigation system. Canals that can irrigate the land have been allocated for the canal command area. In this land allocation, the local people considered the basic principle of land elevation. Again land is managed in large basins (locally called Banno) mostly square or rectangular in shape, about 50 to 150 Jarebs ( two Jareb is equal to one acre). Each basin prepared by about 3 feet high and 5 feet wide borders locally called Lath. All lands were non-surveyed. Lands are rich having alluvial fertile soils.

About 50 per cent population of more than 35 villages indirectly related with the agriculture of Sole Nai irrigation system. As agriculture is not a full-time occupation here, only one crop is harvested on Nai and tubewell water due to uncontrolled water system, therefore they spend their time in bhan-making.

A great provision for use of water lifting machines could be developed after consolidating the check structure with regulators. Along with this tube wells could be developed along the Sole Nai. Water lifting machine could be used up to the availability of water in the Nai after that tube wells could be used to save the cultivated crops.

Huge water wastage, soil erosion, an ill-organizes water supply regulation are the main drawbacks of the local water distribution system. This is all due to the absence of a properly organized regulatory system. With the help of best and extensive regulatory check structures water flows can be diverted for extensive flood irrigation initially.

A regulatory system ensures the water availability for domestic use, this will check the migration rate in the area. An improved irrigation system will bring prosperity to the common people and enable them to invest more to sustain the available resource.