the systematics, morphology, distribution, biology, economic importance and conservation of the spiny eel ( mastacembelus mastacembelus ) of iran are described, the species is illustrated, and a bibliography on this fish is provided. the single species is distributed in southern iranian basins, including karkheh, karun, jarrahi and helleh river basins, mostly part of the tigris river and persia...

Water resources in arid and semi-arid regions are heavily influenced by climate change, water shortage, water regulations, and increased water demands. Monthly discharge is one of the most important factors in hydrological studies. Some of the basins are not equipped with adequate hydrometric equipment. In such a case, average monthly discharge could be estimated by regional monthly water balan...

the response of karoun basin in lumped and semi-distributed simulation were compared. also, the flood intensity of the sub-basins and the effects of physical parameters on flood hydrograph have been investigated. results demonstrated that there was no significant difference between the characteristics of flood hydrograph in lumped and semi-distributed simulation. also, results showed that the f...

We consider three-dimensional discrete dynamical system, obtained by the iteration of a noninvertible map of , which simulates the time evolution of an oligopoly game with three competing firms. The model is characterized by the presence of several coexisting stable equilibria, each with its own basin of attraction. In this paper we face the question of the delimitation of the basins and the de...

Evidence supporting an intense early bombardment on the Moon in addition to the traditional Late Heavy Bombardment at ~ 4 BY ago include the distribution of N(50) Crater Retention Ages (CRAs) for candidate basins, a variety of absolute age scenarios for both a “young” and an “old” Nectaris age, and the decreasing contrasts in both topographic relief and Bouguer gravity with increasing CRA. Crat...

Transport networks are found at the heart of myriad natural systems, yet are poorly understood, except for the case of river networks. The Scheidegger model, in which rivers are convergent random walks, has been studied only in the case of flat topography, ignoring the variety of curved geometries found in nature. Embedding this model on a cone, we find a convergent and a divergent phase, corre...

[1] Numerical landscape evolution models driven by uniform vertical uplift often develop a static drainage network and a precise balance between uplift and erosion. Small-scale physical models of uplifting drainage basins, however, continually reorganize by ridge migration and do not reach an ideal steady state. Here I show that the presence or absence of persistent drainage migration in a bedr...

[1] The oldest, deepest, and largest basin recognized on the lunar surface is the South Pole-Aitken (SPA) basin. In the time since its formation, several processes have modified the original interior of the basin, including the introduction of foreign material by impact basins during the period of heavy bombardment. These later basins redistributed material ballistically across the lunar surfac...

The network architecture of streams and rivers constrains evolutionary, demographic and ecological processes of freshwater organisms. This consistent architecture also makes stream networks useful for testing general models of population genetic structure and the scaling of gene flow. We examined genetic structure and gene flow in the facultatively paedomorphic Idaho giant salamander, Dicamptod...