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Pipe bursts in a drinking water distribution system lead to water losses, interruption of supply, and damage to streets and houses due to the uncontrolled water flow. To minimize the negative consequences of pipe bursts, an early detection is necessary. This paper describes a heuristic burst detection method, which continuously compares forecasted and measured values of the water demand. The forecasts of the water demand were generated by an adaptive water demand forecasting model. To test the method, a dataset of five years of water demand data in a supply area in the Western part of the Netherlands was collected. The method was tested on a subset of the data (only the winter months) in which 9 (larger) burst events were reported. The detection probability for the reported bursts was 44.4%, at an acceptable rate of false alarms of 5.0%. The results were compared with the CUSUM method, which is a general statistical process control (SPC) method to identify anomalies in time series. The heuristic and CUSUM methods generated comparable results, although rate of false alarm for the heuristic method was lower at the same detection probability.

The fundamental physical principles of groundwater flow through porous media are discussed. Analytic solutions are presented for a number of steady flow fields in confined and unconfined aquifers. Transient flow solutions are also presented and include periodic flow, flow to wells, and general flows using convolution. Analytic solutions provide essential insights into flow systems and are important tools both for the design of numerical models and interpretation of their results.

The basic concepts of a transient analytic element formulation for periodic flow are outlined. An example application is given and the application of Cesaro summation of Fourier series for the representation of stepwise pumping records is explored. Application of the analytic element formulation allows for the analytic computation of head and flow at any point in the aquifer at any time. Application of Cesaro summation gives accurate results for pumping wells with stepwise pumping records.

Publisher Summary This chapter demonstrates the application of a new analytic element program for multi-aquifer flow to a shallow coastal plain aquifer system in Greene County, North Carolina, USA. The field site is under investigation to determine the impact of land spraying of liquid hog waste on subsurface and surface water quality. Excess nitrogen as nitrate is being measured underneath the field with a network of monitoring wells, and in the streams by taking discrete samples. Field-scale observations are being used to build watershed-scale models. The purpose of the simplified multi-layer modeling study is to test the hypothesis that simulations based on two homogeneous layers are adequate for understanding the overall water balance, and will form the basis for future estimates of nitrogen-nitrate loadings to streams in this watershed. Preliminary results are presented in the chapter.

The Girinski potential for groundwater flow in stratified aquifers has been extended to allow for a different anisotropic horizontal hydraulic conductivity in each layer. The difference in anisotropy between layers creates a three-dimensional flow field, which may become complicated, for example near wells.

Publisher Summary This chapter outlines a general analytic element theory for steady state groundwater flow in multi-aquifer systems, to present the analytic elements that are currently available for the modeling of multi-aquifer flow, and to discuss new elements that are under development. An analytic element method for multi-aquifer flow may be formulated in terms of a column vector of discharge potentials, where the components of the vector represent the potentials in the different aquifers.

Seawater intrusion (SI) is a global issue, exacerbated by increasing demands for freshwater in coastal zones and predisposed to the influences of rising sea levels and changing climates. This review presents the state of knowledge in SI research, compares classes of methods for assessing and managing SI, and suggests areas for future research. We subdivide SI research into categories relating to processes, mea- surement, prediction and management. Considerable research effort spanning more than 50 years has provided an extensive array of field, laboratory and computer-based techniques for SI investigation. Despite this, knowledge gaps exist in SI process understanding, in particular associated with transient SI processes and timeframes, and the characterization and prediction of freshwater-saltwater interfaces over regional scales and in highly heterogeneous and dynamic settings. Multidisciplinary research is war- ranted to evaluate interactions between SI and submarine groundwater discharge, ecosystem health and unsaturated zone processes. Recent advances in numerical simulation, calibration and optimization tech- niques require rigorous field-scale application to contemporary issues of climate change, sea-level rise, and socioeconomic and ecological factors that are inseparable elements of SI management. The number of well-characterized examples of SI is small, and this has impeded understanding of field-scale pro- cesses, such as those controlling mixing zones, saltwater upconing, heterogeneity effects and other fac- tors. Current SI process understanding is based mainly on numerical simulation and laboratory sand-tank experimentation to unravel the combined effects of tides, surface water-groundwater interaction, heter- ogeneity, pumping and density contrasts. The research effort would benefit from intensive measurement campaigns to delineate accurately interfaces and their movement in response to real-world coastal aqui- fer stresses, encompassing a range of geological and hydrological settings.