The HBV model of these systems may be assessed using the Nash–Sutcliffe efficiency coefficient. A geometric progression of these systems is postulated by Horton’s laws, (15[1])which strengthen Playfair’s (15[1])description of these systems’ incision. (15[1]-5[1])A namesake (-5[1])“continuum concept” models these systems as dynamically stable ecosystems. (15[1])Sharp changes in gradients of these systems called (*) knickpoints can be caused by rejuvenation. (10[1])Strahler (10[1]-5[1])numbers (10[2])were developed (10[2]-5[1])to (10[1])describe (10[2])the bifurcation (10[2])of these (10[1])systems, (10[3]-5[1])which engage (10[2])in downcutting (10[1])to form terraces. These systems are flanked by a (-5[1])riparian zone (10[2])where they (10[1])may (10[2])deposit (10[3]-5[2])eroded (10[2])material (10[1])as alluvium. (10[1]-5[2])For 10 (-5[1])points, (10[1])name these hydrological systems whose branching defines (10[1])basins that drain to a delta. ■END■ (10[10])