The Albanian Watershed Assessment Project (AWAP) aims to protect Albania’s natural resources. This project is funded by USAID through US Forest Service. From the initial 12 watersheds, the final assessment concentrates on Shkumbini and Vjosa River watersheds located in the Central and Southern Albania. Most of the damage associated with flooding and sedimentation in Shkumbini River could be attributed to the impact of extensive gravel mining and the transport of material already deposited in the river system.
The gravel mining impacts in a river system are best studied by numerical modeling. In modeling such systems, different gravel mining scenarios (different locations, pit dimensions, or timing) are introduced into selected reaches under hydrologic design conditions. Based on simulation results, each option is prioritized for its upstream and downstream effects, the replenishment of scour holes created by mining, bed and bank instabilities due to changes in channel geometry. Appropriate numerical modeling also provides managers tools in assessing effects of removing coarser size fractions from channel bed, as well as introducing additional fine sediment from dredging operations. Through the use of a numerical model, the extent of channel instabilities can be assessed and effectiveness of various mitigation measures can be tested.
In this project, the BRI-STARS model developed by Dr. Albert Molinas, President, Hydrau-Tech, Inc. was used in assessing morphological changes due to various gravel mining scenarios in the Shkumbini River. The study reach for modeling is an 8 km section of the Shkumbini River between Peqin and Rrogazhine as shown in Figure 6. Figures 7 and 8 show typical cross sections computed through time; Figure 9 shows a longitudinal channel profile showing the gravel pit with head cutting advancing in upstream direction and downstream scour.