Urbanization leads to the growth of impervious surfaces, which increases surface runoff, causing pluvial and flash flood phenomena. Furthermore, it significantly limits the infiltration of stormwater into the ground; this, in turn, reduces groundwater supply, ultimately intensifying drought effects. In order to adapt urbanized areas to climate change, the objective is to stop these unfavorable processes and strive for recreating the natural water cycle through developing decentralized stormwater management practices on private properties. An important management instrument that motivates property owners to invest is economic incentives, such as stormwater or impact fees associated with a system of rebates/discounts that depend on the applied stormwater runoff reduction solutions. Herein, we analyze a new economic instrument—a fee for reducing natural field retention—which is planned to be introduced in Poland. We assessed the incentive and funding (income-generating) function of the fee based on the example of the Sudół river catchment in Krakow, Poland. The research involved conducting simulation calculations and assessing the incentive impact through calculating investment Net Present Value (NPV), which is the investor’s response to the proposed economic incentives included in the structure of the fee and the rebate system. This study demonstrated errors and loopholes in the suggested fee rules—too low rates that prevent achieving profitability (negative NPV) for small-scale stormwater retention practices, and incorrect conditions that enable obtaining discounted fees. We also estimated the fee rate that ensures investment profitability.

Changes in the land use of urban catchments and the discharge of stormwater to rivers are causing surface water pollution. Measurements were taken of the quality of discharged stormwater from two areas with different types of development: a residential area and a residential–commercial area, as well as the quality of the Sudół River water below the sewer outlets. The following indicators were studied: TSS, COD, N–NO3, N–NO2, TKN, TN, TP, Zn, Cu, Hg, HOI, and PAHs. The influence of land use on the magnitudes of flows in the river was modeled using the SCS–CN method and the Snyder Unit Hydrograph Model. The results showed an increase in sealing and a resulting increase in surface runoff. Concentrations of pollutants in stormwater and analysis of the potential amounts of loadings contributed by the analyzed stormwater outlets indicate that they may be responsible for the failure to meet environmental targets in the Sudół River. Environmental risk assessment shows that the aquatic ecosystem is at risk. A risk factor indicating a high risk of adverse environmental effects was determined for N–NO3, Zn, and Cu, among others.

The complex integration of water and flood risk management, climate change adaptation, and sustainable planning requires advanced, dynamic tools that are unavailable to most planning offices. This paper aims to demonstrate that the available GIS technologies and large, variable, and diverse datasets (big data) already allow us to create effective, easy-to-use, and, most importantly, cross-sectorial and holistic tools that integrate issues related to planning, flood risk management, and adaptation to climate change. Resulting from an interdisciplinary study of districts in Kraków, Poland, which have been heavily affected by pluvial floods in recent years, the accumulated runoff mapping analysis method proposed in this paper can be considered an effective planning tool that can be used at the initial stage of pluvial flood risk assessment and, above all, for spatial planning analysis and urban design. The proposed tool accounts for a correlation of development, land cover, and hydrological conditions, as well as their impact on vulnerability and the urban climate, while integrating environmental, urban, and social amenities. Intended for preliminary planning phases, it uses open-source software and data, which, although giving approximate runoff volumes, do not require advanced hydrological calculations or costly and time-consuming field research. The method allows studying alternative scenarios that can support the cross-sectorial, inclusive, and interdisciplinary discussion on new developments, sustainable planning, and adaptation to climate change. Most importantly, it can reduce, if not eliminate, issuing decisions that may have negative impacts on urban areas and enhance their resilience before more sophisticated, detailed, and advanced methods are ready for implementation.