The Drin River is the largest and most constant stream (see table 2). Fed by melting snows from the northern and eastern mountains and by the more evenly distributed seasonal precipitation of that area, its flow does not have the extreme variations characteristic of nearly all other rivers in the country. Its normal flow varies seasonally by only about one-third. Along its length of about 175 miles it drains nearly 2,300 square miles within Albania. As it also collects from the Adriatic portion of the Kosovo watershed and the three border lakes (Lake Prespa drains to Lake Ohrid via an underground stream), its total basin is around 6,000 square miles. The Seman and Vijose are the only other rivers that are more than 100 miles in length and have basins larger than 1,000 square miles. These rivers drain the southern regions and, reflecting the seasonal distribution of rainfall, are torrents in winter and nearly dry in the summer, in spite of their relatively long lengths. This is also the case with the many shorter streams. In the summer most of them carry less than a tenth of their winter averages, if they are not altogether dry. _Table 2. Drainage Basins in Albania_ Drainage basin Length of river Area of basin (in miles) (in square miles) Drin 174 2,263* Seman 157 2,305 Vijose 147 1,682 Shkumbin 91 918 Mat 65 964 Erzen 56 301 Ishm 43 244 Buene** 27 623 * Within Albania only. ** Includes Lake Scutari. Source: Adapted from Athanas Gegaj and Rexhep Krasniqi, _Albania_, New York, 1964, p. 8. The sediment carried by the mountain torrents continues to be deposited but, having created the lowlands, new deposits delay their exploitation. Stream channels rise as silt is deposited in them and eventually become higher than the surrounding terrain. Changing channels frustrate development in many areas. Old channels become barriers to proper drainage and create swamps or marshlands. It has been difficult to build roads or railroads across the lowlands or to use the land. Irrigation has been accomplished ingeniously by Albanian peasants for many years, to the degree that they and their expertise have been sought after throughout Europe. Projects required to irrigate or to reclaim large areas of the lowlands, however, are on a scale that probably cannot be accomplished without financial assistance from outside the country.