diff --git a/src/main/java/com/gunshi/project/xyt/mapper/AttResBaseMapper.java b/src/main/java/com/gunshi/project/xyt/mapper/AttResBaseMapper.java
index 6a42317..c0d73bb 100644
--- a/src/main/java/com/gunshi/project/xyt/mapper/AttResBaseMapper.java
+++ b/src/main/java/com/gunshi/project/xyt/mapper/AttResBaseMapper.java
@@ -119,6 +119,15 @@ public interface AttResBaseMapper extends BaseMapper<AttResBase> {
                         """)
     BigDecimal queryMaxRzByStcdAndTime(@Param("stcd") String stcd, @Param("startTime") Date startTime, @Param("endTime") Date endTime);
 
+    @Select("""
+            <script>
+            select
+               max(t.z) from public.st_river_r t
+            where t.stcd = #{stcd} and t.tm <![CDATA[>=]]> #{startTime} and t.tm <![CDATA[<=]]> #{endTime}
+              </script>
+                        """)
+    BigDecimal queryRiverMaxRz(@Param("stcd") String stcd, @Param("startTime") Date startTime, @Param("endTime") Date endTime);
+
     @Select("""
             <script>
                 select stcd,stnm from st_stbprp_b where res_code = #{resCode}
diff --git a/src/main/java/com/gunshi/project/xyt/service/RiverWaterService.java b/src/main/java/com/gunshi/project/xyt/service/RiverWaterService.java
index a3f420c..d3302a3 100644
--- a/src/main/java/com/gunshi/project/xyt/service/RiverWaterService.java
+++ b/src/main/java/com/gunshi/project/xyt/service/RiverWaterService.java
@@ -130,13 +130,11 @@ public class RiverWaterService {
         //最新水位时间往前推24小时水位
         LocalDateTime now = LocalDateTime.ofInstant(tm.toInstant(), ZoneId.systemDefault());
         LocalDateTime dateTime = now.minusDays(1);
-        BigDecimal oldRz = attRvBaseMapper.oldRz(stcd,2,Date.from(dateTime.atZone(ZoneId.systemDefault()).toInstant()));
+        BigDecimal oldRz = attRvBaseMapper.oldRz(stcd,1,Date.from(dateTime.atZone(ZoneId.systemDefault()).toInstant()));
 
-        if(oldRz == null){
-            return vo;
+        if(oldRz != null){
+            vo.setRzDiff(rz.subtract(oldRz));
         }
-        vo.setRzDiff(rz.subtract(oldRz));
-
         //本年最高水位
         BigDecimal maxYearRz = queryYearRzByStcdAndTime(stcd);
         vo.setMaxRz(maxYearRz);
@@ -157,7 +155,7 @@ public class RiverWaterService {
                     0
             );
             endTime = now;
-            return attRvBaseMapper.queryMaxRzByStcdAndTime(stcd,Date.from(startTime.atZone(ZoneId.systemDefault()).toInstant()), Date.from(endTime.atZone(ZoneId.systemDefault()).toInstant()));
+            return attRvBaseMapper.queryRiverMaxRz(stcd,Date.from(startTime.atZone(ZoneId.systemDefault()).toInstant()), Date.from(endTime.atZone(ZoneId.systemDefault()).toInstant()));
         }
         return new BigDecimal(0);
     }