The hindu kush-himalaya (HKH) in the global and marine context: Major estuaries, coast-scapes, ocean coupling, seawalls, over 2 billion people and global (food) security

Abstract

Water and nutrients have global cycles; it’s based on rivers those systems collect and involve land, oceans and the atmosphere. Most rivers end in estuaries where freshwater meets the saltwater. The Hindu Kush-Himalaya (HKH) region features major watersheds and usually those end in extensive wetlands and then estuaries. Many estuaries of world relevance are fed by the HKH watersheds affecting global biodiversity, biomass and carbon sequestration, but also human civilizations! The productivity of rivers and their estuaries can affect human well-being, entire nations, the global economy and even trigger warfare. Here an overview is shown for river outflows, the major estuaries in the HKH region such as the Yellow Sea, the Mekong, the Sea of Okhotsk, the deltas of the Ganges and the Indus. Central Asian wetlands fed by rivers but not ending in oceans are also covered in this assessment, e.g. Aral and Balkash Lakes. While mapping the HKH area has been ongoing for centuries, precise maps of the dynamic wetlands and estuaries, within a good time frame and available - are rare making impact assessment tricky. Even for tsunami forecasts (where human lives are lost and precise coastline maps are needed with a 1 m accuracy or better) such data rarely exist. Man-made climate change- namely melting glaciers, floods and brackish water inflow - are creating major changes in those millennia-old life-systems and human societies. The status and connectivity of those estuaries are discussed and how they affect global society. Arguably, we are facing a global river, estuary and ocean crisis still to be addressed.