CASE: SOIL BUNDS IN PAKISTAN 6.7 CASE: SOIL BUNDS IN PAKISTAN

SOIL BUNDS: MOST COMMON WAY OF DIVERTING WATER Diversion cum guide bunds: In upper part of river, where slope is higher, water force is higher and there are mainly gravel and coarse sand deposits Crossbunds cum guide bunds: In lower part of the river, more gentle slopes, sandy-loamy deposits, water velocity is less

SOIL BUNDS: DIMENSIONS OF SAD/GANDIS IN DI KHAN Length Height Width Draban Zam (in mtr) Sad Swad 351 3.2 10.4 Sad Rabnawaz 754 7.0 12.0 Sad Dinga 330 1.9 15.1 Chaudwan Zam Gandi Abdullah 178 8.0 14.0 Gandi Booki 1350 3.0 Gandi Mullawali 87 4.5 Source: Khan and Marwat, 2004

Constructing soil bunds

Constructing soil bunds Location: Determined by lay of the land Manage water levels and avoid overflow/ flooding In case of cross bund - preferably at angle, try to dissipate energy In case of cross bund -may have upstream offtakes too Construction Look for good loamy soil – avoid gravel and sand Avoid saline soil and do rat control – to prevent piping Develop layer by layer Compaction with bulldozer driving across the bund Protect against animal tresspassing Protect with some vegetation and brushwood Special issue Often flood channels are not well maintained and silted up causing pressure on the soil bunds

SOIL BUNDS: MAINTENANCE

SOIL BUNDS: MAINTENANCE Bulldozer Tractor CCA Draban Zam (hrs) (ha) Sad Swad 410 620 666 Sad Rabnawaz 1000 800 1538 Sad Dinga 400 230 820 Chaudwan Zam Gandi Abdullah 500 644 Gandi Booki 880 1200 769 Gandi Mullawali 20 256 Source: Khan and Marwat, 2004

Reinforcing earthen bunds: Gabions

Reinforcing earthen bunds: plastic sheeting Material Black polyethelene plastic 150-250 micron Cost 0.35 USD/m2 Construction Avoid puncture Use steps to contruct to Avoid slippage Anchor at toe and head Cover with 50 cm soil