Inaugurational Speech :

Prof.Dr.rer.nat. Ir. Thomas Triadi P, ST,M.Eng., IPU, ASEAN Eng.

Geological Engineering Department, Faculty of Engineering, Diponegoro University

The need for clean water in Semarang City mostly comes from groundwater. Many sectors use groundwater as their source of water so the exploitation of groundwater continues to increase and harms the environment. The results of the hydrogeological mapping of the confined aquifer show that the confined aquifer flows from the south to the north/northeast of Semarang City. Hydrogeochemical analysis shows that groundwater in confined aquifers has a pH value from neutral to alkaline and the taste of water is from very good to salty based on the value of electrical conductivity. Several chemical parameters exceed drinking water quality standards. The main composition of cations is composed of the elements Na+, K+ and Ca2+ and the main anion, namely Cl. The results of multivariate statistical analysis show that 9 parameters affect groundwater quality, namely: TDS, DHL, Hardness, Ca2+, Fe2+, Mn2+, K+, Na+, and Cl. Of the 9 variables, 2 factors were found that affected groundwater quality, namely seawater intrusion factors which included the variables TDS, DHL, K+, Na+ and Cl- and lithological and anthropogenic factors including hardness parameters, Ca2+, Fe2+ and Mn2+. Groundwater management needs to be directed at a balance between conservation and utilization of groundwater that is integrated into policies and patterns of environmentally sound water resources management. Communities use groundwater as a source of water because it has relatively better quality than surface water and does not require treatment. Groundwater is also considered cheaper and easier to obtain. Groundwater is over-exploited in most urban areas. As a result, groundwater is one of the resources whose availability is increasingly limited. Efforts to reduce the use of groundwater have been made, such as the use of surface water managed by regional drinking water companies. However, the production of clean water from regional drinking companies originating from surface water is not sufficient to meet the demand, so the companies continue to exploit groundwater to increase their production of clean water. Apart from that, problems regarding the poor service coverage of water companies coupled with the lack of enforcement of permits have made many industries and housing use groundwater on a large scale. Data from Idris (2019) shows that raw water sources in Indonesia still use groundwater. The problem of groundwater management is caused by competition in the use of groundwater by various parties because the development of population and industry tends to increase, but the availability of groundwater tends to remain the same. In addition, legal uncertainty results in supervision and control that is not carried out optimally and incompatibility of groundwater use with spatial planning.

Seeing the large use of groundwater in Indonesia has an impact on the availability and quality of groundwater. Utilization of groundwater that is not environmentally sound will harm groundwater conditions. The primary impact that arises as a result of improper water management is reduced groundwater availability. Furthermore, further impacts may arise such as land subsidence, seawater inflow to the mainland (rob) and seawater intrusion into the groundwater layer (seawater intrusion) which can occur especially in coastal areas. The impacts that arise will result in wider damage to the groundwater environment, such as a decrease in groundwater quality.

According to the IEC (Indonesian Environment Center), there are 3 aspects of groundwater management, namely utilization aspects, conservation aspects and control aspects. These three aspects are interrelated and cannot be separated.

Groundwater management activities can be carried out in several ways, including:

  1. Construction of monitoring wells online/real-time to observe the groundwater level and its quality
  2. Construction of Deep Absorption Wells and Shallow Infiltration
  3. Mapping of Groundwater Potential and Configuration as well as Mapping of Groundwater Utilization and Conservation zones
  4. Supervision and Socialization of Groundwater Utilization Control
  5. Numerical modelling of groundwater flow and the movement of contaminant particles