Hydraulic design of collector drains under egyptian conditions

1The growing demand for food to feed the world’sincreasing population has put great stress upon the agriculturalcommunity world-wide. Research into improved seed varietiesand farming methods progress daily.At the same time waterresources and agricultural projects are being implemented tobring more land under c~ltivation.Faced with the pressure ofincreasing food demand,any decline in the productivity ofexisting agricultural lands is vie~ed as a serious problem inmeeting this demand.With the advances in soil physics and in hydrologyduring the last 50 years,the knowledge and understanding ofthe causes,nature,and harmful effects of excess water in agri-cultural land,as well as of the remedial measures to be taken,have improved ’greatly.Agricultural drainage enterprises mav be planned toserve several different functions,including control of salinityor improvement of traff1cability,especially in the humid regions,the primary purpose of drainage is to optimize crop yield.Theoverall probl~m of developing drainage design criteria may beconsidered in ~erms of three distinct phases:the physics ofwater movement through the soil,the physiology of plant resp-onse to the root environment,and the engineering problem ofeconomical design providing a desirable soil condition.Many agricultural lands do not have sufficient nat-ural drainage to drain away excess water due to rainfall orirrigation.A prime requirement for successfully irrigatedagriculture lands is the development and maintenance of a soilzone in which the moisture-oxygen-salt balance is favorablefor plant growth.A simple but comprehensive definition of adequatedrainage is the removal of excess water and salt from the soilat a rate which will permit normal plant growth.Adequate drain-age also may be defined as the amount of drainage necessaryfor agriculture to be maintained successfully and perpetually.