The Indus Civilization (Cambridge History of India, Supplementary Volume) c8.9

c8.9

The problem does not in fact lend itself readily to objective argument. The presence of ruined dams or *gabarbands* in the vicinity of some of the south Baluch chalcolithic sites suggests the likelihood of significant association, and, since these dams are numerous, stone-built, up to 8 ft. wide and 300 yds. or more in length,¹ they represent a sustained attempt to restrain and pond back seasonal drainage, implying on the one hand that the rainfall was somewhat more abundant there than to-day and on the other hand that it was sufficiently precarious to necessitate careful hoarding and control. Here it is clear that a disturbance of the settled population and interruption of its routine would at once deprive a district of much of its verdure, and, in view of the high importance of plant-life in the transpiration of moisture, would be expected to have some considerable reaction upon the local climate.² To balance one factor fairly against another is not an easy task. It may be suspected that flood-water farming played at one time an important part not unlike that of a traditional "Indian" system still available for study in the western United States.³ In this system crop-areas are chosen so that the local rainfall may be reinforced by the overflow of water derived from higher ground, care being taken that the flood-water neither attains such a velocity as to wash out the crop nor carries such a load of detritus as to smother it. The selected area is at a point where waters derived from a stream-channel spread out in a sheet, producing an expanse of moist and fertile alluvium. The main element of uncertainty lies in the varying depth and extent of the stream-channel from season to season, the eroding force of flood-water, and the consequent shifting or even obliteration of the cultivation area, with the result that once thriving farms and even small towns in New Mexico have not infrequently had to be abandoned. It is possible that some of the Baluch hill-villages may have ended in comparable circumstances, and alternatively that the *gabarbands* were a more or less effective counter-measure. In similar fashion the Spanish settlers, with their superior equipment, attempted to control the "Indian" flood-farming methods by damming and ditching, with variable success.⁴