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. Changes in land use from vegetation to non-vegetation in the Lasoso watershed contribute to an increase in the run-off coefficient caused by inundation during the wet season. Therefore, engineering is required to reduce discharge from surfaces. This study seeks to optimize land use in order to manage flooding. This study employs the paimin (modified) method with three different scenarios: Business as usual (BAU), simultaneous, and discrete. Results indicated that the BAU scenario has throughfall and retention capacity values of 15.55 percent and 19.39 percent of the total watershed area, respectively. scenario-2 (simultaneous) decreased throughfall and increased storage capacity (15.35 and 24.65%, respectively); scenario-3 (discrete) also improved. Comparing throughfall values reveals that the discrete simulation (- 0.0020) is greater than the simultaneous scenario (-0.008), whereas the retention capacity has the same value (0.0020). The discrete simulation is superior to the simultaneous simulation in terms of optimizing its use for flood management in the Lasolo catchment.


Introduction
Climate change, alongside natural calamities, flooding, and landslides, is one of the most significant issues of our time (Kan et al., 2019). Among these natural hazards are floods caused by climate change and rising temperatures as a result of global warming, as well as the sudden and torrential rainfall that cause catastrophic flooding (Gagui et al. 2023;Dharmawan et al. 2023). Floods are natural disasters that frequently occur in a region with a particular magnitude and duration, and they have become a critical problem in watershed management (Herath and Wijesekera, 2020), due to natural factors (rainfall, topography, etc.) and human activities (Firdaus and Koestoer, 2022). Ecosystem damage and economic losses have resulted from flood disasters caused by intense rainfall and impermeable soil (Jawad and Al-Abiadh, 2019) and aided by irresponsible land use. Ecosystem degradation has a significant impact on environmental balance and biodiversity loss (Muhsin et al, 2011), while economic losses are estimated to reach tens of billions of dollars annually and millions of lives are lost (Wang et al, 2022).
Lasolo watershed is one of the watersheds located on Sulawesi Island, with a total area of 601,168.75 hectares (BPDAS, 2022). The average height and duration of flooding in this region are 5,626.3 ha, 1.50 m, and 72 hours, respectively, during the wet season. This is the result of the conversion of forest land to mining. In 2019, the mining area was 809.33 ha (KLHK, 2019), while in 2022, the mining area was 352,934.38 ha (BPDAS). This means that there has been a substantial increase. This condition has an effect on the carrying capacity of the watershed, thereby diminishing its ability to support the livelihoods of the local population. In order to enhance the welfare of farmers, it is necessary to optimize land use through management initiatives.

Materials and Methods Study Location
This research was carried out in the Lasola Watershed. The entire territory comprises 601.168.75 ha and stretches from 2045'93" to 3031'96" south latitude and 121047'73" to 122008'91" east longitude. Administratively, the studied area consists of three provinces: Southeast of Sulawesi (North Konawe Regency, Konawe Regency, and North Kolaka Regency), Central of Sulawesi (Morowali Regency), and South of Sulawesi (East Luwu Regency). Utilized data included rainfall information and several thematic maps, including land use and topography.  (3) the third scenario (discrete), an increase in the area of protected/ conservation forest and a decrease in the area of other land uses. This research uses 3 scenarios in designing the model, (1) the first scenario, business as usual to describe existing conditions; (2) the second scenario (simultaneous), an increase in the area of protected/ conservation forest by 1% and a decrease in the area of other land uses by 0.25%; (3) the third scenario (discrete), an increase in the area of protected/ conservation forest and a decrease in the area of other land uses by 1%.

Results and Discussion
The phenomenon of flood disaster is very complex and difficult to fully understand, therefore, an abstraction is needed in its management. The abstraction in question is placing the phenomenon into a model. The flood management model uses a land use optimization approach. This is because land use contributes to flood water supply by 40% (Paimin et al. 2012). Vegetation land has good infiltration capacity so that the flood water supply is lower than nonvegetation land.
Land use in the Lasolo watershed is classified into 5 types of land use, namely protected forest/conservation forest (311,316.05 ha), production forest/plantation (107,557.06 ha), yard bush (102,910.54), paddy (63,237.30) and Build up (16,147.80) (KLHK, 2019). This shows that this area is still dominated by protected forest/conservation forest which is located in the upstream area, while other types of use are in the middle and downstream areas. Build-up area continues to increase in line with the increase in population (Kete et al, 2019) and mining, along with that, other land uses have decreased. Changes in land use due to continuous exploitation have resulted in infiltration capacity and an increase in settlement flows so there is the potential for flooding. Therefore, efforts are needed to optimize land use by managing throughfall to become surface runoff, then calculating the retention capacity to store rainwater into groundwater.  07% and 0%). The build-up is assumed to have no retention capacity. Overall, land use in the Lasolo watershed in managing flood supply into surface water and infiltration as groundwater is (15.55% and 19.39%). Rainwater that falls into a watershed with vegetated conditions has good infiltration capacity so that the flood water supply is low, on the other hand, non-vegetation land (build-up) is high. Optimization of land use in scenario-2 is also used in scenario-3, but in this scenario, there is an increase in the area of protected/conservation forest and a decrease in the area of other land uses by 1%. The results of land optimization analysis by intervening in protected/conservation forest and Production Forest/Plantation lands show that there is a decrease in the throughfall value of the existing condition by 15.47% and an increase in retention capacity of 24.53% with a difference of 0.08%. then intervention was carried out on Yard Bush land resulting in throughfall values and retention capacities of 15.39% and 24.61%. This shows that intervention on Yard Bus land in reducing throughfall values and increasing retention capacity is better than Production Forest/Plantation. This condition also occurs in paddy fields, where there is a decrease in throughfall values of 15.31% and an increase in retention capacity of 24.69% with a difference of 0.24%. It can be concluded that changes in forest area affect the behavior of water flow, the wider and denser the vegetation, the lower the potential for flooding and the availability of abundant water resources.
The conversion of vegetation land to non-vegetation in the Lasolo watershed has recently continued to increase so it harms the hydrologist conditions of a watershed. During the rainy season, floods occur because the watershed is unable to absorb, store, and distribute rainwater in the rainy and dry seasons. In addition, there is an increase in the rate of sedimentation and a decrease in the supply of clean water in the upstream area. The conversion The results of the build-up/empty land intervention in managing floods showed that there was a decrease in throughfall values and an increase in retention capacity of 15.23% and 24.77%, respectively. This intervention is carried out through re-vegetation on empty land which has recently been increasing as a result of changes in the behavior of people who were formerly farmers, now turning into mining employees. In addition, the existence of mining causes the economic value of the land to be high, to obtain community land rights to tear down forest areas as a result there is an increase in the area of empty land. In the Build up/empty land area, it is carried out To obtain land rights, the community remodeled (tear down forest) the forest area, increasing the area of empty land. In the Build up/empty land area, it is carried out To obtain land rights, the community tear down forest, resulting in an increase in the area of empty land. In the Build up/empty land area, it is carried out vegetation enhancement, tree planting actions, afforestation efforts, and future restoration campaigns (Fazaa et al, 2022), moreover, it is also necessary to engineer repairs to drainage channels and construct infiltration wells to allow rainwater to pass into groundwater and soil stabilizers (Kete et al 2020).

Conclusion
Land use management must regulate spatial patterns and structures in the Lasolo watershed, particularly the link between protected areas and cultivation areas and other forms of land use. This is done to reduce the frequency of frequent flooding in this region. The objective of land optimization is to reduce runoff flows to storage capacity. Existing land use contributes throughfall and retention capacity values of 15.55 percent and 19.39 percent, respectively, of the total area. The land use optimization model indicates that scenario-3 (discrete) has a lower throughfall value than scenario-2 (simultaneous), namely -0.0020 -0.0008, indicating that the discrete simulation is more effective than the simultaneous simulation at reducing the throughfall value. while the retention capacity of these two techniques is equally effective in increasing storage capacity with a value of 0.0020. Thus, it can be concluded that flood management in the Lasolo catchment makes excellent use of the discrete method.