zones humides d’intérêt biologique – Exemple: marais d’Harchies

Stream ordering Quantitative way of studying streams. Developed by Horton and then modified by Strahler. Each headwater stream is designated as first order stream When two first order stream combine, they produce second order stream Only when two streams of the same order combine, the stream order increases by one When a lower order stream combines with a higher order stream, the higher order is retained in the combined stream

Potential evapotranspiration (PET) is the amount of water that could be evaporated and transpired if there was sufficient water available. Evapotranspiration can never be greater than PET, but can be lower if there is not enough water to be evaporated or plants are unable to readily transpire.

the Penman-Monteith equation requires daily mean temperature, wind speed, relative humidity, and solar radiation to predict net evapotranspiration. principe de parsimonie (dans la démarche de modélisation).

800 mm.

nous pouvons jouer sur: - connaissance des principaux postes, - choix des especes ligneuses à planter, - intensification des préc (cf projet Geshem par exemple).

Time of Concentration Different areas of a watershed contribute to runoff at different times after precipitation begins Time of concentration Time at which all parts of the watershed begin contributing to the runoff from the basin Time of flow from the farthest point in the watershed Isochrones: boundaries of contributing areas with equal time of flow to the watershed outlet

Time of concentration (TC; hours) for small agricultural watersheds

SIG de plus en plus employés en modélisation hydrologique

Exemple d’un modèle numérique de terrain (MNT) appliqué au calcul des réseaux

Routing a hillslope hydrograph through the network 3. When these are combined, the outlet hydrograph is more drawn out, and the peaks from A, B, C do not coincide 1: Rainfall is transformed by the hillslopes into a hydrograph which is delivered throughout the network . 2: Hydrographs from A take longer to travel to the outlet than those from B, and those from C arrive sooner still.