These surges tend to last for longer periods of time than hydrologically controlled surges. The Pfafstetter Coding System is a hierarchical method of hydrologically coding river basins. The viability for hydrologically based renewable sources of energy is higher in flood-prone regions. Wet prairies and wet savannas are hydrologically similar. It may also commonly become weedy in hydrologically altered systems such as canals and reservoirs. The former southern part of the IJsselmeer is now the hydrologically separate Markermeer. Hydrologically, the valley has three features. These are called Alaskan-type surges and it is suspected that these surges are hydrologically controlled. Hydrologically, the Tularosa Basin is a closed basin; no streams flow out. So, hydrologically speaking, the Hussars Fountain is the true source of Speyerbach. These basins are hydrologically linked to the Snake River. Geographically and hydrologically the Neretva is divided into three sections. The lake may be hydrologically connected to the larger Kraken Mare. Geographically and hydrologically the Neretva is divided in three sections. Compared with its two headstreams, this source of the Danube is, however, hydrologically insignificant.