Rivers of Lebanon: Significant Water Resources under Threats

Lebanon is known by tremendous water resources, and this has been often viewed from the considerable number of rivers (i.e. 14 rivers). These rivers are characterized by small catchments and short length. The estimated average annual discharge from these rivers is approximately 2800 million m3. Due to the sloping terrain of Lebanon; however, it was estimated that more than 75% of water from rivers is unexploited it mainly outlets into the sea. The majority of water use from the Lebanese rivers implies domestic, agriculture, as well as some other rivers are used for hydro-power generation where they contribute by about 20% of electricity needed for Lebanon. Lately, and added to water pollution, there is abrupt decline in the discharge from these rivers estimated to more than 60% of their average annual discharge. This unfavorable situation is attributed, in addition to the changing climate, to the anthropogenic interference is the most affecting one and it is represented by over pumping from these rivers and form the recharge zone for groundwater and springs that feed these rivers. This chapter aims at introducing a discussion on the existed challenges on the Lebanese rivers and the proposed and their impact.

Ecohydrology: An Integrative Sustainability Science

The dynamic of the water cycle in catchments is determined by climate, geology, geomorphology, plant cover ad modified by agriculture, urbanisation, industrial development and hydroengineering infrastructure. Up until the end of the 20th century, water management was dominated by a mechanistic approach, focused on the elimination of threats such as floods and droughts and providing resources for the society with little to no regard for the impact this approach had on the ecosystem. Highlighting of water as a key driver of ecosystem dynamics, and further ecohydrology which highlights water/biota interactions from molecular to catchment scale provide a new perspective, new tools and new systemic solutions for enhancement of catchment sustainability potential WBSRCE (consisting of 5 elements: Water, Biodiversity, Ecosystem Services for Society, Resilience and Culture and Education).

Perspectives of Hydrologic Modeling in Agricultural Research

For decades agricultural research was done in the field or laboratories, but with the rise of computer science, hydrologic modeling became another essential tool for environmental impact studies. Many types of models can be used, each with its strengths and weaknesses in terms of accuracy, speed, and amount of input data needed. Models can be used on different scales and simulate very different processes. Based on a literature review, APEX (Agricultural Policy Extender) and SWAT (Soil and Water Assessment Tool) models are the most popular for environmental research in agronomy. An important share of modeling work in agronomic studies is focused on pollution research, mainly nutrient and pesticide leaching and soil erosion processes. Other topics include simulating the effects of irrigation and other agricultural practices and studying the impact of extreme weather events and climate change. When working with model results, it is crucial to be mindful of inevitable uncertainties and consider them during interpretation. Modeling is gaining importance in agronomic research in Slovenia, with many studies done in the recent decade and more underway.