Development of a method of robust rain gauge network optimization based on intensity-duration-frequency results

Abstract

Abstract. Based on rainfall intensity-duration-frequency (IDF) curves, fitted in several locations of a given area, a robust optimization approach is proposed to identify the best locations to install new rain gauges. The advantage of robust optimization is that the resulting design solutions yield networks which behave acceptably under hydrological variability. Robust optimization can overcome the problem of selecting representative rainfall events when building the optimization process. This paper reports an original approach based on Montana IDF model parameters. The latter are assumed to be geostatistical variables, and their spatial interdependence is taken into account through the adoption of crossvariograms in the kriging process. The problem of optimally locating a fixed number of new monitoring stations based on an existing rain gauge network is addressed. The objective function is based on the mean spatial kriging variance and rainfall variogram structure using a variance-reduction method. Hydrological variability was taken into account by considering and implementing several return periods to define the robust objective function. Variance minimization is performed using a simulated annealing algorithm. In addition, knowledge of the time horizon is needed for the computation of the robust objective function. A short-and a longterm horizon were studied, and optimal networks are identified for each. The method developed is applied to north Tunisia (area = 21 000 km 2 ). Data inputs for the variogram analysis were IDF curves provided by the hydrological bureau and available for 14 tipping bucket type rain gauges. The recording period was from 1962 to 2001, depending on the station. The study concerns an imaginary network augmentation based on the network configuration in 1973, which is a very significant year in Tunisia because there was an exceptional regional flood event in March 1973. This network consisted of 13 stations and did not meet World Meteorological Organization (WMO) recommendations for the minimum spatial density. Therefore, it is proposed to augment it by 25, 50, 100 and 160 % virtually, which is the rate that would meet WMO requirements. Results suggest that for a given augmentation robust networks remain stable overall for the two time horizons.

Drought severity–duration–frequency curves: a foundation for risk assessment and planning tool for ecosystem establishment in post-mining landscapes

“…Risk assessment based on the design rainfall concept is commonly used as a standard tool by engineers to design infrastructure such as storm water drains, flood mitigation levees, or retarding dams (Chebbi et al, 2013;Hailegeorgis et al, 2013). This research paper aims to demonstrate how these concepts can be used for ecosystem rehabilitation, providing a quantitative estimate of ecosystem rehabilitation failure due to water deficit.…”

“…The design drought tool proposed in this paper is an adaptation of the intensity-duration-frequency (IDF) analysis of rainfall events, a standard tool used by engineers (Hailege- Chebbi et al, 2013). Our new term "design droughts", characterised by drought severity-durationfrequency (SDF), is based on the severity of droughts (cumulative negative values of a particular drought; see Fig.…”

“…The recurrence interval is defined as the average inter-occurrence time of any geophysical phenomena and is calculated with long-term time series data (Loaiciga and Mariño, 1991). Recurrence intervals of rainfall events greater than the average are commonly used by engineers to derive intensityduration-frequency (IDF) design estimates for building hydraulic infrastructure such as roofs, culverts, stormwater drains, bridges or water dams (Chebbi et al, 2013;Kuo et al, 2013;Hailegeorgis et al, 2013). IDF design rainfalls are crucial for estimating the risk of hydraulic infrastructure failure and for maximising infrastructure efficiencies (Smithers et al, 2002).…”

Generation of Monthly Precipitation Climatologies for Costa Rica Using Irregular Rain-Gauge Observational Networks

“…Various methods of rain-gauge network performance have been developed using kriging interpolation techniques. For such methods, known as variance-reduction techniques, the performance evaluation of a rain-gauge network focuses on reducing the error variance of the average field value over a certain domain [33][34][35]. Most of these techniques take into account the number and location of rain-gauges to yield greater accuracy of areal precipitation estimation with minimum cost.…”

Rainfall Network Optimization Using Radar and Entropy

“…Shaghaghian and Abedini [12] selected an optimal subset of stations in the network by using Kriging, factor analysis, and clustering techniques to achieve the optimum rainfall network. Chebbi et al [13] identified the optimal network using an intensity-duration-frequency curve and a variance-reduction method. Related works based on entropy since Krstanovic and Singh [14] is widen and undergoing [15][16][17][18].…”