Pengantar Teori Dasar Air Tanah MK. Managemen Air Tanah Program Magister SDA Pengantar Teori Dasar Air Tanah Ir. Moh Sholichin MT., Ph.D Website; water.lecture.ub.ac.id

Siklus Hidrology

Groundwater Flow… … Baseflow

Grafik aliran air tanah sbg base flow ke waduk

Terminology Airtanah

Berbagai Jenis Aquifer

Akuifer adalah lapisan batuan dibawah permukaan tanah yang mengandung air dan dapat dirembesi air. Akuifer adalah formasi geologi atau grup formasi yang mengandung air dan secara signifikan mampu mengalirkan air melalui kondisi alaminya. Batasan lain yang digunakan adalah reservoir air tanah, lapisan pembawa air. Todd (1955) menyatakan bahwa akuifer berasal dari Bahasa Latin yaitu aqui dari aqua yang berarti air dan ferre yang berarti membawa, jadi akuifer adalah lapisan pembawa air.

Confined and Unconfined Aquifers

Airtanah Artesis/sumur artesi

Berbagai Types…

Hydraulic Head air tanah Pressure: Where: r = density of water (kg m-3) g = gravitational acceleration (m s-2) hp = pressure head hp a ht Total hydraulic head (ht): z datum Where: z = elevation hp = pressure head

Darcy’s Law Darcy’s Law defines groundwater flow: where: Q is discharge (L3 T-1) kv is the hydraulic conductivity (L T-1) A is area of flow (L2), and dht/dx is the gradient of pressure, or head

Hydraulic Conductivity (kv) Hornberger, 1998

Groundwater Development

Groundwater/Surface Water Connections Gaining Stream In systems with high degree of groundwater/surface water connectivity (highly transmissive sediments) Pumping Well Implications: Quality implications – contaminant transfer Stream temperature Quantity implications: Groundwater pumping will “pull” water from surface Groundwater pumping less regulated than surface water Note:: this is why important to understand flow processes in systems Manage groundwater as surface water (conjunctive use) Examples: Snake River Plain, Deschutes in Oregon Ex:: Sea water intrusion Cone of Depression Groundwater

Recharge Zone Protection Example Unconfined Aquifer Recharge Zone Confined Aquifer landfill Municipal well field Piezometric surface Gravel Clay flow Clay

Berbagai kemungkinan arah aliran air tanah Gaining stream Effluent stream Losing stream Influent stream Perched losing stream Flow-through stream Dingman

Hyporheic Zone Zone where water is exchanged between surface and groundwater Controlled by geomorphology (upwelling and downwelling) Biochemical processing: water quality & habitat issues Temperature