Rainwater is an abundant source of water, especially during the rainy season. But otherwise if it is not managed properly, it can lead to disasters, such as floods or landslides. Therefore it is very important to harness rainwater by doing the best way, ie by the rain harvesting and then infiltrating the water back into the ground. Many countries have shown good results in the use of rainwater for various purposes. Dominican Republic, Singapore, Japan, China, Thailand and Indonesia are 7 countries which have a lot of implementing rainwater utilization system very well. Rainwater can be used as a source of clean water to meet the drinking water needs. Artificial recharge for rain water lets the water goes to infiltrate back into the soil is a powerful effort to maintain and preserve the ground water potential. Besides, infiltration of rainwater into the soil also can prevent land subsidence. Because of the importance of rainwater management system, it should be included in the educational curriculum both for elementary to upper secondary level. Similarly, the obligation for proper implementation must also be supported by adequate rules or regulations. Keywords : Rainwater management, artificial recharge.

According to Cook, drainage basin characteristics factor yielding high surface stream are 1. Relief 2. Infiltration 3. Landuse, and 4. Drainage density. These physical parameter is use to determine runoff coefficient of catchment area, with application of Geographical Information System (GIS) application on Ciliwung catcment area above Depok. Steps to analyse of runoff coefficient are scoring of each classification of relief, infiltration, landuse and drainage density, and then all of the four maps which have score are overlay to become a map of unit land. Runoff coefficient hereinafter is calculated and found out that runoff coefficient of Ciliwung catchment area is 0, 58.   Katakunci : GIS, SIG, metode Cook, metode Bridge Branch, runoff coeffisient, catchment area, DAS, Ciliwung, relief, infiltration, landuse, drainage density, informasi, peta tematik.

Coastal Aquifer System of Jakarta consist of unconfined aquifer layers, confined aquifer I and  confined aquifer II.  Resources of  groundwater is very important for Jakarta City, for drinking water, industry, hotel, government offices and various other facility. Important considering of    groundwater resources of Jakarta hence needed an effort to preserve the groundwater and awake its continuity by conducting a system management of groundwater. Model used for the management of groundwater system of aquifer coastal referred as Groundwater Model Simulation and Optimization of Quasi Three Dimension ( OPT-Q3D). Model simulation and optimization represent computer model of quasi-three dimensions with method of finite difference used for the operation of infiltration of sea water. This model can conduct current simulation of groundwater flow, head of fresh water and brine, and describe the movement of interface fresh water and sea water. The model can also make optimization of system aquifer with single or multi layers.  Jakarta Groundwater Basin assumed consist three layers of aquifer separated by impermeable layer. Applying of groundwater simulation model in Jakarta can give information regarding balance of groundwater, head of freshwater, head of  brine, interface brine and freshwater, map of brine distribution and bargain in each; every aquifer. Herein after model optimization will yield various information able to wear upon which consideration to manage the amount of pumping of optimal ground water every area in each layer of aquifer, amount of optimal pumping, optimal freshwater head, head of optimal brine and map of infiltration.  Kata Kunci  : Air Tanah, Pengelolaan, Intrusi Air Laut, Modeling

Evaluation of chloride (Cl-) content and electric conductivity  (EC) of ground water in aquifer system is one method to identify salt water movement in aquifer system, which occurred as a result of changes in hydraulic equilibrium which cause by temporary variation of natural recharges and pumping of ground water at many layered aquifers.Salt water movement in Jakarta aquifer system is evaluated based on mapping of chloride content at 500 mg/L and EC at 1500 m mhos/cm in many bored well during period of 1990 – 2000. In the beginning chloride content and EC is in value only and with the addition of attribute data, namely coordinate, it could be used as input data. By using software namely SURF, the above input data is simulate to have a contour map of chloride and EC. Overlapping of the contour map to Jakarta base map will result in thematic map of chloride and EC distribution which represent salt water movement at Jakarta aquifer system.   Key word : Aquifers, Aquifer system, Chloride (Cl-) , Electric Conductivity (EC), Map, Hydraulic Equilibrium, Ground water, SURF Software.

Areas of Jakarta, Bogor, Tangerang and Bekasi (Greater Jakarta) is an area with high rainfall (2250 -2500 mm/year). The rain that falls in this region often cause flooding problems in the area of rice fields, settlements and even in downtown. Rain is a gift from God to be utilized to the maximum extent possible for everyday purposes. Rain Water Harvesting is an attempt to capture rainwater that falls on the roof. In this study, use of the roof area of about 300 -500 m2. Precipitation that falls on the roof is channeled and put into storage, by first filtering done to reduce the dirt. The volume of rain water storage for each location is 10 m3, medium intensity rain (15-20 mm/h), sufficient to meet the storage within a few hours. Rain Water Reservoir are equipped with water pump which has a capacity of 25 liters/minute, the water can be used for flushing toilets and spraying crops. If Rain Water Reservoir is full, water overflows into the Artificial recharge well. The results of analysis with Kostiokov calculation method used to calculate the infiltration rate of Artificial recharge well and calculate the cumulative volume of infiltration at the Artificial recharge well. Results of tests conducted are as follows: a). In Depok, the infiltration rate of Artificial Recharge Well is about 12 mm/minute and was relatively stable at 140 minute (2 mm/minute). It also has the ability to recharge  450 liters of water in 140 minutes. b). In South Jakarta, the infiltration rate of Artificial Recharge Well is about 11 mm/minute and was relatively stable at 160 minutes (2.5 mm/minute). Artificial Recharge Well has the ability to recharge  480 liters of water  in 160 minutes. c). In Bantarjati, Bogor,  Artificial Recharge Well have the highest capacity, namely 45 mm/minute and was relatively stable at 260 minutes (2.5 mm/minute). Artificial Recharge Well has the ability to recharge 1000 liters of water  in 150 minutes. Rain Water Harvesting Development Efforts and Artificial Recharge Well very useful to overcome inundation in residential areas, especially during heavy rain, because it can reduce the volume of surface water into the channel simultaneously. Keywords : Rain Water Harvesting, Infiltration, Artificial Recharge.