1. Workshop ’Building healty soils and preventing erosion in Ghana and Belgium’ Sirigu; Ghana Institute of Organic Farming Programme: - Introduction - The problem of erosion & dry boreholes - Are Swales a solution? - Discussion - Examples of Swale Farms

2. Ghana Organic Agricultural Projects www.ELPG.nl

4. Map of Campus GIOF  Area of 2 Ha  Problem 1: After a (heavy) rain shower, water runs off to river.  Problem 2: Dry Boreholes!!  Solution ?  By Swales on Contour Lines:  - Soil absorps water - Cash + Food crops can grow - Increased income - Feed the Boreholes! GIOF school Garden Stream GIOF Office etc. Borehole o New Borehole o

5. Rainfall in North Ghana  The average rainfall per year in Sirigu: app. 1000 mm

6. Erosion  Erosion caused by water flow (rainfall) or wind  When soil is saturated - Run off occurs Wind erosion Wind en seawater erosion Water flow erosion

7. Erosion at GIOF site

8. Swales on contours could be a solution to Erosion, Land Rehabilitation and Dry Boreholes What is a Swale?

9. What is a Contour Line? Where are contour lines at the GIOF site? Legend: Constructed swale Swales to be constructed

10. Details of a Swale

11. A-frame: Creating contour lines  How to create contourlines? - by measuring the inclination angle  Using an A-frame

12. A contour line is not a straight line. It is a level line: that means if you walk along it you will not be going up or down the slope but staying at the same level. Usually it will curve with the shape of the land. Example of a Contour Garden

13. Method of natural tree watering Applicable on GIOF!!!

14. Water-Infiltration rate measurement  The Single (or double) Ring Infiltrometer method is used.  (Ho – He) : T x 1440 = m/d (meters per day)  1,92 meters per day - Reduction factor is used

15. Lay out of a Swale for Arid Climates 2 m 1m 0,2 m Storage capacity swale: 0,2 * 2 * 0,5 = 0,2 m ³/m¹

16. Results Width Swale (m) Heavy shower per day (mm) Potential infiltration (m ³ / d) One Swale2 (+1)50118 Width between swale 450237 Total 355 Width swales Total rainfall (mm) Potential infiltration (m ³ / year) Infiltration whole campus 4100020.000

17. Design a Multifunctional Swale Farm on a Slope  Function:  Control Erosion  Rehabilate the soil  Increase Soil organic matter  Produce food (tree-food, crops, vegetables, mushroom, fodder etc)  Produce fodder  Create micro climates  Create shade

19.  Final Result of the swale: - 62 meters long  Total capacity: - 62 * 0,2 = 12,4 m ³ - Time to run dry of the swale = 1 hour