6.9 Case: Hadramawt Improved Traditional Engineering

YEMEN WADI HADRAMAWT Rainfall isohyets

Hadramawt: special characteristics Extremely low rainfall (50 mm/year) Very irregular and often heavy floods Special efforts to avoid that large floods destroy command area and residential area) much attention for spillways( Groundwater and hence recharge is important

MANY LARGE FARMER-BUILT STRUCTURES IN HADRAMAWT

Al Powirigat Traditional Dyke Water Master In many systems the traditional structures have been improved through a mix of modern and traditional techniques

Special structures Diversion structures Bunds and dykes Traditional abutments Spillways Recharge bunds Command area structures Water distribution structures Field to field overflow structures Low flow field intakes

DIVERSION STRUCTURES Bunds and dykes Traditional abutments Spillways Recharge bunds

Traditional dyke at Hadramaut

Traditional diversion dyke – at angle with the flow of the river

TRADITIONAL DYKE: SPILLWAY/ OVERFLOW

AL ROMALYA TRADITIONAL WEIR REINFORCED WITH CONCRETE SPILLWAY WITH STEPPED STONES AL ROMALYA TRADITIONAL WEIR REINFORCED WITH CONCRETE

FLOOD CHANNEL INTAKE TRADITIONAL ABUTMENT BREACH-ABLE EARTHEN BUND TO BREAK IN HIGH FLOODS AND RELEASE FLOOD WATER INTO THE RIVER

TRADITIONAL ABUTMENT

LIME MORTAR STRUCTURES

TRADITIONAL INTAKE IN HADRAMUAT

MOZA SIBHAM DYKE REINFORCED WITH TRADITIONAL ABUTTMENTS

MODERN ABUTMENT FOLLOWING TRADITIONAL DESIGN

COMBINED GABION SPILLWAY WITH TRADITIONAL ABUTTMENT

GABION SPILLWAY

Gabion spillway and traditional intake at gar-Sudan area (at wadi Dowan) Hadramawt

TRADITIONAL LOW RECHARGE WEIR TO SLOW DOWN AND SPREAD FLOODS

COMMAND AREA STRUCTURES Water distribution structures Field to field flow structures Low flow field intakes

WATER DISTRIBUTION: WATER IS DIVIDED PROPORTIONALLY IN SMALL CHANNELS

WATER DISTRIBUTION: GATES USED ON SOME OF THE SMALL CHANNELS TO CLOSE SUPPLIES AFTER AREA IS SERVED

FIELD OVERFLOW STRUCTURE

FIELD TO FIELD FLOW STRUCTURES (SPILLWAY)

FIELD OUTLET STRUCTURE

FIELD TO FIELD FLOW STRUCTURE (INLET OR OUTLET

UNDERFLOW STRUCTURE TO CAPTURE VERY SMALL FLOWS

FIELD SYPHON FOR FIELDS HIGH ABUTMENT