## 5 Conclusions  
In the last decades, computing power has increased drastically. As we have laid out in detail, imaging methods have now become affordable, which directly optimize spatial stacking operators for maximum coherence within the pre-stack data. The benefit-cost ratio is particularly attractive for near-surface seismics. A global simultaneous grid search enables the comprehensive evaluation of a wide range of velocity model configurations. By systematically testing various combinations of three stacking parameters, the presented CRS stack approach identifies the parametrization that optimally describes a seismic reflection event in midpoint and offset dimensions. The iterative refinement process incorporates both global and local searches to ensure a computationally efficient approach while maintaining high accuracy. The global search identifies promising regions in the stacking parameter space, while the subsequent local optimization fine-tunes the parameters for the stacking process. To achieve a well-balanced compromise between computational efficiency and stacking parameter quality, we presented a hybrid method, which combines a global search for the two parameters of the CDS operator with a local optimization of the three parameters of the CRS operator. Using the global simultaneous three-parameter optimization as reference, we showed that this global-diffraction/local-reflection search algorithm can deliver nearly identical results, while reducing the computational cost by an order of magnitude. As a case study, we presented data from a hydrogeological survey, targeting the definition of predictive groundwater flow models for effective water resource management. A comprehensive comparison with results of conventional methods demonstratedthe significant improvement in resolution and reflection continuity that can be obtained, together with a far more accurate velocity field, by using CRS stacking with spatial velocity analysis. The method clearly imaged two key reflection events \(\gamma\) and \(\alpha\), interpreted as the boundary between Holocene and Pleistocene alluvia and the top of the Paleozoic bedrock, respectively, in a fully data driven way, despite the challenges posed by the noisy low-fold near-surface data.  
Conceptualization, Z.H. and G.P.D.; methodology, Z.H.; software, Z.H.; validation, G.P.D. and Z.H; formal analysis, Z.H; investigation, Z.H.; resources, G.P.D. and Z.H.; data curation, G.P.D.; writing--original draft preparation, Z.H.; writing--review and editing; Z.H and G.P.D.; visualization, Z.H. and G.P.D.; supervision, Z.H. and G.P.D.; project administration, Z.H. and G.P.D.; funding acquisition, Z.H. and G.P.D. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Autonomous Region of Sardinia grant number ex art. 9 L.R. 20/2015, and the APC was funded by the University of Cagliari.  
The data presented in this study are available on request from the corresponding author.  
The authors are grateful to [PERSON] for valuable discussions and to an anonymous reviewer whose detailed and constructive feedback strengthened this work.  
The authors declare no conflicts of interest.