# Spatial Optimization of the Groundwater Quality Monitoring Network in the Kingdom of Bahrain

^{*}

## Abstract

**:**

## 1. Introduction

## 2. Materials and Methods

- (1)
- Data collection and preparation

- (2)
- Conducting a univariate statistical analysis for the data of the existing network

- (3)
- Conducting structural analysis on the data of the regularly monitored wells from the AEWRD using the Geostatistical Analyst Extension of ArcGIS software

_{i}) is measured value of the state variable (i.e., salinity) at coordinate x

_{i}.

_{0}is the nugget variance, and C

_{0}+ C is the sill. C

_{0}and C represent the random and spatial components of variation, respectively.

- (4)
- Kriging the salinity using the existing observation points of the monitoring networks and the constructed model variogram using the Geostatistical Analyst Extension of ArcGIS Software

^{j}

_{0}is the weighting function of each point j to be used in the estimation of point x

_{0}and where γ(x

_{i}− x

_{j}) is the variogram value for the distance between x

_{i}and x

_{j}.

- (5)
- Calculating the error of kriging estimation using the Geostatistical Analyst Extension of ArcGIS Software

_{0}is given as

- (6)
- Adding new locations of monitoring well(s) for the aquifer based on the maximum error and other criteria

- (7)
- Kriging groundwater salinity using both the regularly monitored wells and the newly added well(s) and calculating the associated error of estimation

- (8)
- Repeating steps 5 and 6 until no significant reduction in the error is observed

## 3. Results and Discussion

#### 3.1. Statistical Analysis

#### 3.2. Structural Analysis

#### 3.3. Kriging and Kriging Error Analysis of Existing Network

#### 3.4. Upgrading the Existing Monitoring Network

## 4. Conclusions

## Author Contributions

## Funding

## Data Availability Statement

## Acknowledgments

## Conflicts of Interest

## References

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**Figure 3.**Frequency distribution of the existing groundwater salinity data of the Khobar aquifer zone.

**Figure 5.**Experimental and fitted spherical model variogram of the existing wells in the Khobar aquifer zone. Parameters of the fitted model variogram (Equation (3)) are nugget (C

_{0}) = 498,540; radius of influence (a) = 2205 m; and sill value (h ≥ a) = 1,838,140.

**Figure 6.**Cross-validation results of the fitted model variogram in estimating the TDS value of the existing monitoring wells in the Khobar aquifer zone.

**Figure 7.**Uncertainty map of (

**a**) existing monitoring network of the quality of the Khobar aquifer zone, (

**b**) stage 1 of observation well augmentation, (

**c**) stage 2 of observation well augmentation, and (

**d**) stage 3 of observation well augmentation.

**Figure 8.**Trends in the maximum and average errors of the Khobar aquifer zone by network upgrading stage.

Parameter | Value |
---|---|

N | 38 |

Mean | 4543 |

Median | 4501 |

Variance | 2,971,181 |

Standard Deviation | 1724 |

Minimum | 1540 |

Maximum | 9616 |

Skewness | 0.8 |

Kurtosis | 0.8 |

**Table 2.**Maximum and average errors calculated for the estimation of water quality of the Khobar aquifer zone using the existing monitoring network and the various stages of adding new wells.

Stage | Maximum Grid Error | % Change in Maximum Error | Average Grid Error | % Change in Average Error |
---|---|---|---|---|

Existing wells (15 regular and 23 industrial wells) | 11.27 | - | 4.32 | - |

Stage 1 (44 commercial residential compound wells) | 4.83 | 57.12 | 1.80 | 58.35 |

Stage 2 (9 farmer wells—1) | 2.66 | 44.91 | 1.46 | 18.75 |

Stage 3 (9 framer wells—2) | 2.48 | 6.95 | 1.38 | 5.48 |

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**MDPI and ACS Style**

Al-Zubari, W.; Al-Shaabani, A.; Abdulhameid, N.
Spatial Optimization of the Groundwater Quality Monitoring Network in the Kingdom of Bahrain. *Water* **2023**, *15*, 2169.
https://doi.org/10.3390/w15122169

**AMA Style**

Al-Zubari W, Al-Shaabani A, Abdulhameid N.
Spatial Optimization of the Groundwater Quality Monitoring Network in the Kingdom of Bahrain. *Water*. 2023; 15(12):2169.
https://doi.org/10.3390/w15122169

**Chicago/Turabian Style**

Al-Zubari, Waleed, Ali Al-Shaabani, and Nadir Abdulhameid.
2023. "Spatial Optimization of the Groundwater Quality Monitoring Network in the Kingdom of Bahrain" *Water* 15, no. 12: 2169.
https://doi.org/10.3390/w15122169