LIKE many other parts of the country, Dera Ismail Khan has been badly affected by the recent floods. The devastation is worse than that caused by floods in 2010. The main reason of heavy floods was the long monsoon spell in the area, especially over the adjacent mountains.
Dera Ismail Khan is the southernmost district of Khyber Pakhtunkhwa (KP), which lies in the foothill of Sulaiman range on the west and river Indus on the east. The piedmont plains in the foothill of the range, locally called Rodh Kohi, mostly depend on the water received from the mountains as floods after rainfall in the catchment, which is utilised for agricultural production and drinking purposes after being stored in big embanked fields and ponds.
The magnitude of water storage mostly depends on the amount of rainfall received in the huge watershed which extends throughout the range. The water, after rains in the watershed, rushes down through the opening or gate, called zam. There are five of them in the Rodh Kohi system of Dera Ismail Khan; Gomal, Tank, Sheikh Haider, Daraban and Chaudhwan.
The people of Rodh Kohi mostly wait throughout the year for rain in the mountains so that they may utilise the floodwater in their fields, especially during the monsoon season. After the rain over the mountains, water finds its way to the plain due to the steep landscape. The water is diverted through big earthen check dams that are locally called gandi.
The check dams are constructed in a head-to-tail sequence. After irrigating the field in the head, the check dam is breached so that water may be consumed in midstream and then downstream areas. Each year floodwater of varying magnitude is received and utilised for growing crops, and the whole system is in the domain of spate irrigation, which, in effect, means it is flood-based.
After the construction of Chashma Right Bank Canal, a huge area is now being irrigated in the east, while the western part still remains flood-based. In the irrigated area, to avoid damages caused by the floods, the older riverines of Rodh Kohi system are converted into drainage channels. This serves as drain for excess canal water and as passageway for floods to the Indus.
The unpredictability and unknown magnitude of the flood make it more precarious. In the current season, the heavy and prolonged rainfall in the catchment was the major factor responsible for the massive flood. The water came out with greater force due to greater mass and velocity.
This greater magnitude of flood was difficult to be diverted or controlled by the earthen check dams, for they got breached quickly and water swiftly moved downstream. As most of the land has remained fallow without any agriculture crop, shrubby trees, etc., due to scarcity of water, also the soil having clayey hard surface, accelerated the flow of water without any resistance.
Due to continuous siltation in the drainage channel, the capacity to flow of the flood was low, which built enormous pressure on the channel banks, and the banks were worn away easily.
After the shattering of banks, the flood spread speedily with greater pressure in all directions, causing severe destruction to villages, roads, houses, and everything else.
There is a dire need for taking onboard all the stakeholders to probe into the different causes that triggered such massive devastation, to improve coordination among different government departments, and to effectively manage Rodh Kohi channels.
Construction of big water reservoirs is also needed, but detailed feasibility reports have to be first worked out, especially in terms of siltation, water distribution and biodiversity.
Last but not least, the floods of 2010 and 2022 have issued a clear warning that undeveloped and inattentive rural areas pose great threat to urban areas. This makes the development of Rodh Kohi system all the more essential.
Dr Qudrat Ullah Khan
Dera Ismail Khan
Published in Dawn, September 24th, 2022